Why does my stomach hurt after having sex before my period?

Small stomach pain after intercourse before menstruation may be due to pelvic inflammatory disease, cervicitis, endometritis and other diseases.
1. Pelvic inflammatory disease: usually due to Chlamydia trachomatis, Neisseria gonorrhoeae and other pathogenic infections, and also related to poor hygiene, sexual activity, direct spread of inflammation in neighboring organs and other factors. Patients often appear lower abdominal pain symptoms, and will be aggravated after sexual intercourse and activities, some patients can also be manifested as pre-menstrual coitus after small stomach pain.
2. Cervicitis: mainly due to Chlamydia trachomatis or Neisseria gonorrhoeae infection, and also related to tampons, hormonal imbalance, multiple sexual partners and other factors. Most patients do not have obvious symptoms, some patients may have increased vaginal discharge, abnormal vaginal bleeding and other symptoms, and will also be manifested in the lumbar and abdominal pain, pain during sexual intercourse and so on.
3. Endometritis: usually due to bacterial infection and other pathogens, and related to gynecological surgery, sexual life, lower genital tract infection and other factors. Patients often have lower abdominal pain, leukorrhea, lower abdominal distension and other symptoms, often aggravated after activity and sexual intercourse.
It is recommended that patients with pre-menstrual pain in the stomach after intercourse, timely identification of the cause of the disease, rational treatment.