Diarrhea for over 4 hours straight. Help?

Earlier this evening, I ate 6 out of 8 slices of a large New York style double cheese pizza. Getting back home around 7:30, i began having awful diarrhea. I could not even sit for more than ten minutes without having to go to the bathroom. It's been over 4 hours and I haven't stopped. I've been to the bathroom about 15 times and its always a yellow/brown straight liquid that burns something awful. I just started drinking gatorade and also have some ginger ale. Should this help, how long will the diarrhea continue, and should i be worried?