I've had experience with one of mine being extremely high-energy, then turning lethargic and not moving, losing power, refusing to eat and passing shortly after. it was late into the night, no sober drivers and the only emergency vet being 3hrs drive away; and i couldn't do anything for him.
When i had my first ever sweet gigantic cuddlemonster become ill, the first thing i noticed was his sudden limping. He was a healthy boy prior to that, hadn't been injured or gotten sick anytime else, and could tolerate all sorts of not-so-healthy foods that he was given. Most french lops i've known of have stomachs made of full steel.
I was alarmed immediately but my parents weren't on board with going to the vet, saying that he'd perhaps just sprained his ankle during a jump or something. I didn't have much say about the situation, and i don't have a liscense, so all i could do was wait and hope the situation would get better. A week went by and still no improvement, so dad finally booked a time to the local vet. Xray was done and some antibiotic was given. It wasn't the right dose nor time long enough, so nothing improved, say for a bit of a better appetite. The bulge on his knee had actually grown and begun causing him some mobility issues.
Back to the vet again. With the widest needle they had, a milligram of thick, white sludge was extracted, but the cause was never properly explained to us. Even if it was, i couldn't remember. All i recall is that they told that the knee would've needed operation that they didn't dare do lest something go wrong and my boy would never be able to use affected leg again. They told us to look for a mrre experienced vet but didn't refer us to any particular one. So we booked into one that dealt with rabbits. Waited many weeks and wasted 100e for another xray and injection that did nothing. We were told there not to touch or massage the foot. So we left it alone, waiting for whatever they injected to take effect. It didn't, so we booked for a third vet, waited two weeks and then went in, hoping to find a cure that would let our bun return to his normal self. We were told right off the bat that leaving that foot for its own accord was terrible advice given by that vet. As 1 1/2 months had passed since the first signs, a new xray was done, which showed that the knee we were hoping to treat-its joint had been completely destroyed by whatever bacteria had come to live inside. Our bun was also dealing with severe weight loss, messy bum and unidentified skin pests, the possible treatment was expensive ( an estimate of 500e just for the amputation, not including pain/wound management, weight gaining helpers, skin treatment etc that would need to come with it) and even then the vet couldn't say for sure if our big boy would make it out alive and continue to live a decent enough tripod life.
We found it best to let him go.
I was always blaming myself for not rabbit-proofing enough (i'd put the blame on one of the many times he'd fall off my bed while digging at it), not looking for best vets (the best being in the capital, whose traffic dad despises), for not pressing for faster/earlier checkups by the vet. I was putting myself down for going to that one horrible vet, and critisizing how i didnt see the red flags of that vet. I'd also made a promise that i wouldn't let my rabbit go, which i broke, even though i believe that it was indeed the better choice for him.
Why didn't i do more research? Why didn't i stand up for him more? Why didn't i suspect the second vet? Why did i let myself wait so long for the third vet? If he was gone, what would be left for me in this world?
I couldn't let go of the deep connection i'd developed with that special rabbit, and i still cry when i think of him. But i was constantly reminded that i had another living being who needed me to be there, to care for and bond with him. As spontaneous and unthought-of purchase as my first rabbit, the second one came home with us in the same newly bought carrier i'd planned to take the ill one back home with. I'd noted the sign of rabbits for sale on our way to the vets, and i'd managed to coax dad into checking there to try and see if there was a rabbit that might appeal to us, to patch the hole that losing Musti had created. We couldn't find one there, so we went back to the one we'd bought young Musti from just about a year prior. From there, we found Storm, and he came with us just two hours after i'd bid farewell to the sick one.
I'd gotten a newfound urge to make his life a significantly better one than Musti's. It's worked well thus far- the booger is still alive and kicking, is with is second bondmate, and booked for his third vaccine+health check. He's now an indoor rabbit, and gets enough freeroaming and is far from ''solitary confinement''.
All this wouldn't have been possible if Musti didn't have to go.
So the knowing that by his life having gone, other rabbits got a chance at better care, a more fulfilling life and a loving home, it eases my heart.
Even when i knew little and didn't know to push the vets for more, i did the best i could and knew of at that time.
With time, my emotions had calmed and i could see the reason- nothing would change with me blaming myself, it would only harm me.
Time cannot be reversed, This made me value all the good times and the wonderful special quirks of his. I only wish i could've taken more pictures and recorded more videos.
Healing takes time. Loss teaches us things. Dear ones should be valued- only when you lose something do you realize how precious said thing is.
Dad proposed that he could have a tombstone made for him. It's a wonderful sentiment and it helped me see that although dad doesn't say it often, he still loved my rabbit dearly. Mum who usually likes to talk a lot, didn't say anything when we buried him. It was too hard for her to talk. She, too, despite everything inappropriate she said, loved him very much. It made me feel a bit easier knowing that my parents cared for him deeply, even if they didn't say it to my face.
We who are the closest to our pets learn to know almost instinctively when something is off with them. It's a much more valuable skill to rabbit owners than those of dogs or cats, as rabbits are supreme at hiding their illness. You were right to talk of your concerns, and you can take pride in being a bunny parent that has learned the skill of detecting subtleties of illness. You can take pride in being a rabbit parent that cared so much. Compassion for smaller animals is what many unfortunately lack.
Stay safe, take time to heal, stop blaming yourself and make sure to keep all the fun, awesome, unique memories of your bun somewhere where you'd never forget them. (The most impressive memory I have of Musti is that, aside from overwhelming curiousity and affection, kissing my tears away when i was sad and miserable, even at the vets, and that he was super tolerant and accepting as i learned to safely handle him, is that he snored. He would always flop to his side, fall asleep deeply and then begin snoring. I got a 5-second sound clip of that and it's one of the most precious bits of stored memory that i have of him.)