Hello, You are having stomach cramps and brown mucus after menstruation. Brown discharge may be an early sign of pregnancy in some women due to implantation bleeding. Some women also experience low abdominal pain, cramps and discomfort. You are suggested to wait for a couple of days and then get pregnancy test done with the first morning mid stream urine. You can also consult a gynecologist to confirm pregnancy. You may have to get few required blood tests and USG (Uterus with fallopian tubes) done. Other causes of brown discharge in case you are not pregnant are when old blood mixes with the normal vaginal discharge, brown mucus discharge may be seen. Minor vaginal tear or removal of old endometrial tissue may cause brown spotting or discharge after sex or menstruation. Take care of your hygiene. Avoid rough sex. Stay away from addictions if any. If you are entertaining multiple sexual partners, it may be a sign of STD, get clinically assessed. You will be treated accordingly. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician