I had the same rapid beats. Ended up getting a stress test and showed I had mitral valve prolapse. After heart monitor wearing for a month I taped my episodes on machine, phoned it in and they found I had supraventricular tachycardia. Nothing serious but could either put up with it, take medicine the rest of my life or go to Hershey, PA(chocolate) and they performed an electrical physiological study on heart and through a catheter zapped the misfiring nervees inside my heart. Sounds scary, but it really was nothing.My advice, get checked by a heart doctor, just to be safe.Also, once you look up mitral valve prolapse, funny how IBS and that have some similar symptoms.