Hello, Sometimes, old blood in the form of brown color comes out, this is old blood that is forced out when the woman experiences an orgasm. However, it can be because of other underlying medical conditions like STD, bleeding after sex is commonly seen if a woman is infected with STI like chlamydia or gonorrhea, etc. Get STD tests done to stay on the safer side. If reports come positive, you will be treated with antibiotics or antivirals, whatever suitable. Avoid stress of any kind emotional or physical. Take iron, minerals and protein rich food. Take well-cooked whole cereals to help gain weight. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician