Sounds as if your heart rate increased temporarily and was working harder. If it is not often or does not cause problems I would only consult a physician on the phone.
What Does It Mean When I Keep Feeling A Heart Beat In My Stomach? I've Had No Signs Of Pregnancy. Am I Pregnant?
If you don't have pregnancy then the beats which you are feeling can be the peristaltic movements of digestive tract. These movements push the food from one part to other. Usually these movements are not felt but some some times in some peoples can feel it. For your cycle irregularities take hormonal support.