The vet took some blood and did some x-rays. She confirmed that his kidney values haven't changed, they are still slightly high, just a bit over the normal range. I was happy the values are steady and not rising. With his vomiting and not wanting to eat, I feared the numbers might be worse. We've switched his food to kidney diet in hopes that helps.
A few years ago, we did an x-ray of his belly and learned then that he has arthritis in his lower back. It was time for another image. This one showed continued degeneration in his back and it showed his knees are actually much worse off than his back. That probably explains why he takes the stairs so slowly. Movement like that probably causes pain. We've started him on a different pain killer in hopes it helps him manage the pain a bit better.
Purrs for my precious Buddy are appreciated