A great diet to get diarrhea under control is "equal amounts" of boneless, skinless boiled chicken breast and canned pumpkin (NO spices or additives), fed 3 or 4 times daily in small amounts.
I'd nix the Science Diet and get a good digestive enzyme and probiotic to help with his loose stools. This id kibble contains corn, chicken BY-Products (which can include the intestines PLUS the stool in it!
) and the 7th ingredient is powered cellulose which is wood pulp!
Sounds like he is not assimilating his food properly if he is going after poop! One of the below products added to his food will help this.
Great products with quality ingredients to try:
: Carmspack Working German Shepherds, Feed-Sentials
*Digest All PLUS
: The Wholistic Pet
Hope this helps!