Thanks for writing in,
Diarrhea is very common in dogs. As long as he is doing fine otherwise, not vomiting etc, then you can try feeding him boiled chicked breast and rice which is very easy on his stomach. You can also add some plain yogurt to his diet which will replace the good bacteria that should be in his Gi tract. as far as the scooting goes, this may be due to the irritation from the diarrhea, or it can be due to full anal glands. You can call and ask your vet tech to express them and they will be able to tell you if they were the problem or not, and you won't have to see a vet, but the next best thing! I hope this helps!
Dog Veterinarian
Veterinarian, Dog/Cat Veterinarian