Hi!
Obviously it is extremely important to bring them to the vet ASAP, but knowing you can't, these are things I suggest...I would say start by inspecting both rabbits, making sure the blood actually came from their urine and not their ****** or a wound or other.
Are you bunnies drinking enough water? Try to stay near by and observe if maybe only 1 rabbit is drinking the water, and the other is not. Just because the water bowl is emptying, doesn't mean that both rabbits are drinking. Dehydration can cause the urine to be darker and will also make their urine more concentrated, possibly in calcium. It essentially helps their kidneys dilute the urine. If one is not drinking enough, try to increase their water intake by drenching their greens in water, without removing the excess, so they get the extra bit of water while eating. You can also give greens that have higher water content like romain lettuce. Also make sure to change their water 1-2 times a day to make sure it is always fresh. Also make sure to wash their water bowl frequently, because they might not drink from it if it gets smelly or dirty.
Look out for any stones (may be very small like a grain of sand or big) or if the urine seems to be thick or paste-like, or if there are whitish stains. These most likely could be calcium crystals, from when their kidneys have trouble removing excess calcium, leading to a build up, creating a stone. These can be caused by a urinary tract infection (causing inflammation, making it hard to excrete the calcium), dehydration, excessive calcium intake, or even being overweight and sedentary. Look at everything you are feeding them and try to limit their calcium intake as much as possible, which is high in most pellets, certain greens, kale, spinach, brocoli, alfa-alfa, treats, supplements, etc. Passing a calcium stone could have caused the bleeding. Other important signs to look out for that may be related is difficulty urinating, reduced appetite, reduced stool (make sure its not all from the other rabbit), reduced energy, soiled fur, teeth grinding or hunched position (pain). However, be aware that these are all general signs and symptoms that may be cause by numerous other medical emergencies.
If it happens again, you can test the pee to see if it is actually blood or not. You can pour hydrogen peroxide on the urine, and if it starts to slightly foam or bubble, it's an indication that it is in fact blood, which is an emergency (STAT)!
Unfortunately, money can be tight and vet visits can be very expensive. However, without knowing the cause, it is impossible to know how much you will have to spend. Depending on the issue, the vet will give you estimates or options of what you can do, which aren't always pricy, and will essentially let you decide what you want to do. I recommend that the bare minimum is to bring them in for an evaluation which is usually around 50$ or less than 100$, i paid 80$ for my rabbit (Canada). If you do, make sure you bring in both rabbits at the same time, since we don't know who it's coming from, especially if they are bonded it will reduce their stress x1000. This may sound harsh, but as a rabbit owner, it is your responsibility to make sure you can provide for both rabbits whether it be food, space, or vet visits, otherwise it is neglect. I'm also currently in a tough spot and I brought in my 9 y/o rabbit for her first vet check up, which I have avoided doing for the past 3 years. I feel 1000x better now that I did, and I don't feel the constant stress anymore of being a "neglectful owner". She has several issues for which I could pay for multiple tests, but I'm taking one step at a time, and I started with her antibiotics which was a priority and it only cost me 50$. Who knows, maybe your bill will be on the lower end. If this happens again, and you absolutely cannot bring them to a vet, please please please look over you what you value and remind yourself that you want to do what's best for the rabbit, and not just for the sake of having a pet. Perhaps ask for a payment plan, start a gofundme, or crowdfunding to get the extra money you need (make sure this doesn't take too much time or drag on, because the longer you wait, the worse the condition will get, and the more you will have to pay). Not sure if they have an SPCA in California, but they often have a program to lower vet bills for people with low income. PLEASE, consider giving your rabbit to a rescue shelter or something along those lines where they might be able to take on the responsibility and properly care for your rabbit if you don't end up taking your rabbit to the vet.
Please give any updates you may have, I'm willing to help!
