I'd get a better food first. Wellness is a good brand and available at Petco. You might have a pup with a sensitive stomach.
Pumpkin (canned) is good for upset tummies. I've used it for diarrhea, vomiting, constipation and it works well. You might also want to try plain yogurt or a diet of rice and boiled chicken for awhile (not sure if this is ok for puppies?).
As far as treats go, you can use:
Small pieces of kibble (helps to have a diff brand than the reg dog food you feed, for variety)
Small pieces of low fat cheese
Cheerios
Small pieces of veggies or fruits (carrots, apples)
Treats that don't have a lot of extra added ingredients. Like treats that are just pure turkey or chicken. There are some on the market that are like "pumpkin and banana" "apple and blueberries" etc. I haven't read the ingredient list (and I can't remember the brand) but they looked good.
Small pieces of low-fat cheese |