Sunce returning from Dominican Republic in May I have been experiencing dizziness, rapid heartbeat and faintness, right before and during a bowel movement. It happened to me one time on the train, and I had to tell a stranger in case I passed out (at this time no clue what was going on). I call them episodes now. From then on I've been to my PCP, a allergist and had an ultrasound. I have for the last few months been now having blood in my stool and loose stools and more increased bowel movements. These episodes are so scary and I never know when they will occur. Any ideas what this can be?