Please help. 16 year old with end stage kidney failure and seizures

[IloveBuster]

Hello, I rescued my American Pitbull Terrier Buster when he was 7 months old. He turned 16 end of September. He is my best friend and my everything and I don’t know how to live without him. September 26 his creatine was at 2.8 and BUN was 65 which doubled since the previous 3 months. 3 weeks later on October 17 it double from that to creatine 4.6 and BUN 111. He gets subcutaneous fluids daily at home and is now on a kidney diet. Initially he wasn’t eating the kidney diet but now he does. (Canned wet food) A few weeks ago he started getting myoclonic seizures. They went away recently for a few days and now are back again. I tried Azodyl for him but as soon as I started it he declined fast and got better once I stopped it. He’s on cerenia for nausea as needed and appetite stimulant. His Dr said his phosphorus levels aren’t too high, only creatine and BUN. I’ll never be ready to let him go but I need to keep him as long as I can and feeling good. Is there any suggestions on what else I can do? He still is alert most days and plays and goes on walks.