Don't give up hope. Flora went into stasis and my vet found a 'mass' in her abdomen. He said it was either a tumor or an abscess. We decided not to open her up to find out because if it was a tumor, there was nothing they could do and if it was an abscess, it could be treated with antibiotics. We just went straight down the antibiotic route and figured that if she didn't improve, it was most likely a tumor. I gave her daily injections for 8 weeks and she was right as rain again.
Hope your bun improves - sending <<<<< vibes >>>>>