What Causes Gastritis, Diarrhea And Nausea During Menstrual Cycle?

Hi, When I had my periods in Feb, it was accompanied by nausea and diarrhea.I went to a doctor who attributed it to food poisoning and gave me meds for the same. It went away after 5 days.My periods were light. This month when I had my periods again it was accompanied by cramps, gastritis, loose motions, nuaseosness(I did nt puke). Wondering what could be the cause?