I worked at a vet's office for over 5 years, and what you're going through is incredibly common. To firm up your dog's stool, you should be giving rice and boiled chicken or ground beef. It'll help firm up the stool until you get the dog food issues worked out (very easy on their belly). As for a dog food, most vet's sell prescription food made for sensetive stomachs (Science Diet, Purina, Royal Canine). Eukanuba makes a sensetive stomach formula that can be purchased at most pet food stores. The vet can also recommend doses for Immodium or Pepcid(yes the stuff we use). If they aren't being more proactive in helping, I would find a new vet. A good doctor should be willing to work with you from home, and not drag you in for office visits every time you need to try something new. Good luck with your puppy. PS-Two of my dogs are on Wellness and it's a great food.

PPS-Puppies need to be wormed multiple times. I assume you're vet has done this, but it could be a parasite.

We had the same problem when we transistioned our dog to Wellness. After she had an accident on our bedroom floor in the middle of the night, we decided we needed to switch her to something else. She went on a "bland" diet for a week or so. Then we slowly (extra slow) transistioned her to a brand called Natural Balance (www.naturalbalance.net) She has done really well on it. We give her the Ultra kind but they also have a kind of dogs with sensitive stomaches. And they have dog treats too.