Try Pet Flora, it saved my puppy from explosive diarrhea and I had tried everything. It also balances the gut and intestines, building a healthy digestive system for young pups!
Check out
Pet Health Care - Natural Remedies For Your Cats & Dogs for more info on the product and I wrote a whole post about it on my blog -
PetFlora, Holistic Digestion Aid | CupOFdog | Dog Site for Dog People
Good luck! It has saved my pups the discomfort and danger of diarrhea countless times!