Rat diarrhea??

This is a baby I saved from the feeder bin at the pet store. He was swaying watching me and I fell in love. Please help he has a wet bum and I think he has diarrhea.

Is his stomach bloated?
what are you feeding him?
How long have you had him?
Age?
(you do know that babies need to live with at least one other baby so if possible get one of his brothers if you did not do so already)
Watch out for dehydration and make sure the baby is getting enough fluids - foods with a lot of fluid, such as organic soy infant formula thickened with baby cereal will help with hydration

If the baby has diarrhea, feeding a bit of canned pumpkin (Not pumpkin pie filling) may help