Folks, the suggestions for rice, chicken, cottage cheese, pumpkin, no kibble, no grain yada, yada, yada ... (fill in the blank) may be good for a simple diarrhea. This problem has been going on for over a month while under the care of a veterinarian and is obviously NOT a simple problem easily treated with diet change.
We're doing a disservice to this dog suggesting things without knowing complete history including previous labs and treatments.
What worked for you with your dog with a simple diarrhea isn't necessarily applicable.
I think WandaLust2's suggestion about a second opinion is a valid one. Chronic problems are really frustrating for you (and your vet too). Keep the communications open and going, this is the fastest way to reach a solution.
Doug, DVM