I had a rabbit that I put to sleep at the age of 4. She was a beautiful Standard Satin. I suspect that the problem with her was inbreeding. She stopped eating, and I took her in and she got her teeth trimmed. Two weeks later, she stopped eating again. I took her back and she got antibiotics and another teeth trim and she was eating again. Two weeks after that she stopped eating. I took her to another vet where she got yet another teeth trim. A little over a week later she stopped eating. The vet did an x-ray. The vet said that there was a big problem with her roots and she wanted to pull all of her teeth. Then I would have to hand feed her. I also had a cat that needed vet care for skin problems, and I was going in debt and having trouble paying my bills. I had my rabbit put to sleep because I felt that a rabbit with no teeth would have quality of life issues, along with digestive issues. The vet was angry with me, but she offered me no financial help. I was a single mother and was having trouble paying my bills. It is hard to know when to stop. You have to balance your needs with your rabbit's needs.
If you adopted this rabbit from a rescue, maybe you can reach out to them and see if they can help you with the medical issues.