Had diaherra for a month, went to the doctor to be checked. They found no viruses and check for c diff. Saw a gi dr, put me on flagyl, Imodium, Zantec, and Zyrtec. I started having horrible abdominal pains from the Imodium. Stopped that and still had abdominal pain but not as bad. After I ran out if flagyl, the diaherra came back and left for a week and I stopped taking zabtec and Zyrtec as well. My diaherria has started back. What could this be?