Have you tried getting them to poop? You need to get a warm cloth/towel and stroke the kittens rump. Stroke where the poop comes out, and also underneath him.
Has he been bloated lately? Feel around his stomach for small lumps or incaved parts. There are usually pet hospitals that can give you over-the-phone advice or at-home emergency numbers for your vet.
Good luck, and I would do a google search. I wish you the best...
I would also look up information on DIABETIC cats/kittens. Look for symptoms and treatment. I have that this site
had some good symptoms.
Lindzey and the Gang