Very Odd Digestive issue.

Question
This is kind of long, I apologize.  I found an APBT/? cross puppy a little over a month ago.  She did really good on the Orijen/Eagle Pack mix and then due to a misunderstanding ended up being fed a very cheap, nasty food for a week before going back on the mix (second change was slow).  That was about three weeks ago.  Since then she has had constant runny stool. I've taken her in to the vet, they found nothing wrong all three times.  I've given her canned pumpkin with no help and over-all I'm starting to get very worried.  Physically she is gaining height/weight and is very active.   She is fast thinking and apparently happy. Any ideas what else I can try?? Or something I may have missed?

Answer
I would do a five day treatment with panacur just in case there might be some worms, or ghiardia going on that the vet missed. It happens sometimes. I would also put her on ten days of flagyl, and ten days of albon or SMZ. Just to be absolutely SURE,
You might also want to go with straight Eagle Pack and see how she does. Orijen is very very high protein and sometimes difficult for puppies to digest without runny poo. Get her on some acidopholous supplements and plain, all natural yogurt twice a day in addition to the canned pumpkin.
A fasting day of nothing but unsalted chicken broth, lots of liquids, unflavored pedialyte might help to jump start the healing.
Hope this helps you get her straightened out.
Cindi