Buford, 3 mths, eats Iams Smart puppy <--- yeah right!! hehe It's what the breeder fed and I didn't want a vet bill by switching foods and having problems. Plus he's small and it doesn't cost alot. I have been looking at Hills Science Diet though. The vet said Purina or the other two I have mentioned would be his recommendation. Buford has had some gas and it has been smelly for such a little guy but he got into the cat food. Which happens to be Purina.
Read on......
My other dog NOT a Pug, a 4.5 yr old Choc Lab (he's the larger variety VS the Am. Field Lab which is smaller and furry-er) was at last check 120lbs, but has lost some because the same vet said to switch to Purina Fit N Trim (or the Sc. Diet ) We went with Purina, it has worked but his "dogpile" used to be medium, now it's a hu-normous mountain. He was on a high protein diet before the switch to Purina, a higher fiber diet that's filled with lots of corn ingredients!!! Corn equals poop, big poop, more frequent poop, and a weird smelling poop. Think about humans we have a hard time digesting corn, so wouldn't a dog too. I hope this helps even though it's not a pug the are both dogs.
Also I read on someones pug page and the vet verified it (I've been there twice this month for the last of his puppy shots, yeh!).... that you could give them chopped up carrots, unpeeled and deseeded apples, and yogurt as treats. The yogurt (mix it with the food) helps with loose stools and diarrehea. The apples and carrots are good for lowfat treats and anal gland health which is important for smaller breed dogs. About the allergy thing could it be the change in atmosphere, I'm sure the allergens were different wherever you came from. I was from FL and never had an allergy problem I move to dumpy old OH and I get both allergy seasons, it sucks!!!