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The brown discharge/spotting could be suggestive of pregnancy, infections like Gonorrhea or Chlamydia, PID, vaginitis, ovarian cysts, uterine fibroids, use of hormonal contraceptives, endometritis, endometriosis, adenomyosis, cervical dysplasia, etc. Only after a careful examination and investigations (vaginal swab/smear test, PAP smear test, hormonal analysis) the exact cause can be made out. The hormonal and blood work-up done will help in ruling out hormonal derangements and bleeding problems. Ultrasound scan will help to rule out structural problems and possibility of ovarian cysts, presence of polyps, fibroids etc. PAP smear will test for cervical erosion/dysplasia and vaginal swab/smear test will help to rule out infective causes. Treatment as needed (based on your examination and investigation results) would be started to help you. If infective cause is detected, get your partner also treated simultaneously to prevent re-infection and avoid having unprotected intercourse while both of you are on treatment course. Visit your gynecologist/obstetrician at the earliest for further evaluation and assistance.
Take care.