Pain in the side of the stomach may be acute appendicitis, or it may be caused by intestinal diseases or gynecological diseases. 1. Acute appendicitis: the cause of its occurrence is mainly due to bacterial infection of the appendix, inflammation, increased seepage around the abdominal wall is stimulated, the formation of acute peritonitis, may appear in the case of pain in the side of the stomach, accompanied by nausea and vomiting. 2. Intestinal diseases: If the pain in the side of the stomach is accompanied by diarrhea, abnormal defecation, or after defecation, the pain is significantly relieved, it may be triggered by irritable bowel syndrome and other intestinal diseases. 3. Gynecological diseases: If there is a pain in the side of the belly, you should pay attention to whether it is a change in the female menstrual cycle, if there is a change in the menstrual cycle and as much as possible, or abdominal pain is closely related to the menstrual cycle, it may be due to gynecological diseases. If there is a small stomach side pain, it is recommended to closely observe, abnormalities in a timely manner to seek medical attention, follow the doctor’s instructions for targeted intervention.