Defiantly skip the gatorade -- it is a huge myth that it's good for people and animals when they are sick. It has alot of sugar in it which upsets the balance of intestinal flora, feeding the bad bacteria, which can be the cause of the problem in the first place.
Boiled chicken and rice is good for a sensitive tummy, but to make the stool firmer I would mix potato, pumpkin, and banana -- all very good stool firmers that won't upset the tummy.

Good luck!