Yesterday i was on the road for about 9-10 hours, and had fast food twice in the day. today i'm having stomach cramps, watery diarrhea, and heartburn ?

Stomach cramps: Stomach cramps and diarrhea after fast food could be due to food poisoning. Check with your PCP.

Not surprising: Fast food tends to be very high in fat. High fat intake will often cause stomach cramps, watery diarrhea, and heartburn; especially in a person whose body is accustomed to a healthier diet. Fast foods are highly processed and contain a lot of preservatives and other additives that can cause stomach problems. Try drinking a lot of water, and a BRAT diet for the next few days.