Well, if the new vet says he can't find anything either, I would say change the litter too. I have a lilac point siamese and let me tell ya, she rules the roost. I used to laugh at that commerical where the cat makes the lady go back and get the "good" litter but thats my little cleo to a 't'. She would 'poop' on the shaggy bathroom rug if she didn't aprove of her litter. She was telling me, she could have made it she wanted to, but she didn't like the environment ya know?

Also, if I try to feed cleo dry food she will walk up to where I'm sitting and yack it up right in front of me. weird eh? If she doesn't like the food she lets me know 'right away'.

But I still adore her, and have been known to drive all over town to find all the flavors she loves...I'm bad..I know...lol

Good luck with maxx

another thing, is the poo normal, or more loose then it should be?
have you changed his diet at all? Are there any new plants in the house he may be upset about?