So after all that, it's his kidneys...
Not much we can do other than keep him comfortable. I am going to get the prescription diet from the vet and see how he does on that for now. If he stops eating and drinking then I'm not going to let him suffer. Two of my previous cats went from kidney failure and it wasn't nice for anybody. He certainly isn't going to get to live as long a life as I would've liked him to and of course am wondering what we/I could have done differently but don't know if there is really anything.