Be careful with the Pepto as it contains aspirin, which can further upset the stomach lining. Canned pumpkin can work both ways, to stop diarrhea or to help constipation, however it is the amount given, and that is always iffy.
FOR DOGS WITH UPSET STOMACHS....I have tiny dogs and whenever they have an upset stomach I feed them 1 to 2 tablespoons of pumpkin. Each time I open a new can I put 2 tablespoons of the pumpkin into individual sandwich bags, next I place all the bags into one freezer bag and store them in the freezer. When I'm ready to use one I just thaw out how many I want to use.