For the last 3.5 weeks I have had severe diarrhea along with intestinal cramping even during the night time. I have been monitoring my diet. I am currently on medications; Vytorin for high cholesterol and Prevacid for acid reflux disease. I have stopped taking these meds for a week to see if they were the issue. My diarrhea continued. My symptoms started after contracting a severe sinus infection. My doctor prescribed, after two seperate visits, an antibiotic for the sinus infection. Two weeks after taking the antibiotics I started experiencing diarrhea. What do you think is wrong?