There are many reasons for stomach pain: first of all, we should see if there is any relationship between stomach pain and menstruation, and stomach pain is not necessarily menstrual pain, or pain before menstruation, sometimes abdominal pain comes from other causes, such as appendicitis, and gastroenteritis, this possibility; another is whether there is pelvic inflammatory disease, in this regard, it is recommended that the next time the pain is checked for blood tests, or check the ultrasound of the abdominal cavity, to exclude the abdominal cavity. Other diseases. If there are other problems, deal with them first before considering the cause of menstruation. If you feel that your stomach pain is closely related to your menstruation and you have stomach pain before each menstrual period, then go to a gynecological examination.