Diarrhea, Stomach Discomfort, Rancid Bowel Movement. Taken Activia. Thoughts?

Drove 12 hours in a vehicle on Sunday, only ate some fried foods--fish, potato s and okra. That evening felt like someone punched me in the stomach. Couldn t eat/wasn t hungry at all. Suffered from terrible diarrea on Monday, still felt like punched. I am able to eat, but the constant pain/soreness below my sternum is very irritating. Diarrea subsided on Tuesday, but still rough bowel movements, pain did not subside. Today (Wednesday) pain still present, plus I have a cold/ flu like symptoms. I can eat without a problem, but I have been having only 1 big BM a day, rancid smelling. Earlier this year I had heart attack like symptoms and found out with an Endoscopy that I have some esophogeal ulcers . Been taking Prilosec for about 2-3 months now. Has taken care of heartburn symptoms altogether. Had sleep study done, and just picked up my c-pap machine, but have a hard time using it right now because of the cold. The main issue is the punched in the stomach pain. I started Activia yesterday to try and help. Thoughts?