Hello, You bleed after sexual intercourse. You have history of having chlamydia, you also had bacterial vaginitis for which you have been treated. You are suggested to avoid rough sex or deep penetrations as it can cause vaginal bleeding due to internal injury, abrasions, tearing, cut or an infection. Cervical polyp, growth in the uterus, cancer can also cause bleeding per vagina after penetrative sex. Since you already had chlamydial infection, you should get re-rested, urinalysis (R/E and C/S), get a routine pap smear, test for HPV done. For chlamydia, test the swab of the discharge from your cervix for culture or antigen testing. Chlamydial infection & STI also cause bleeding. Medical conditions that cause bleeding are cervical ectropion, cervicitis, vulvovaginitis, etc. You are suggested to avoid multiple partners as you are very young and should not get STIs. Always perform safe sex and use condoms. Using water or silicone-based lubricants help prevent bleeding caused by vaginal dryness and friction during sex. Get clinically examined by a gynecologist, get per vaginal tests and required tests and investigations done. Your treatment will depend on the pathology detected. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician