I am sorry for your trouble. Have you paid attention to what you are eating a few days before and right up to your period? Some women tend to eat chocolate or other foods that they normally do not eat and it upsets the digestive process for a time. You take that and fluctuating estrogen levels and voila! an upset tummy. Sincerely, searchin
Are your periods irregular? Do you have any cysts on your ovaries that you are aware of? Have you ever been told that you have an irritable bowel or irritable bowel disease? Does this happen every time you have a period?
It would be wise if you were to make an appointment with a physician--perhaps a gastroenterologist. This is not normal.