Coco's Kidney Failure

I was told that the bloodtest results shows that he has Kidney Failure (CRF - Chronic Renal Failure). The BUN reveals the Toxin levels in cats. When the kidney functions well, the cat's BUN level is between 10-30. Coco's first blood test shows that his was 63 (when it's over 60, they are nauseated). The 2nd blood test came back at 158. By this time, he was looking so bad. He could barely move. His back legs were shaking, and he was drinking air instead of water. I really thought I had to put him down, and I was crying and crying. In the end, after buying every brand of canned food out there, he started to eat a bit. The doctor gave him nausea pills, which might have helped too. He also had Urinary tract infection, so he had to take antibiotics, and at this point, he takes SubQ fluids daily.