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The causes for brown bleeding could be many like PID (pelvic inflammatory disease), genital warts, gonorrhea, Chlamydia infection, menopause, vulvovaginitis, use of contraceptives, uterine fibroids, adenomyosis, ovarian cysts, etc. The exact cause can only be made out with a thorough examination and further investigations. You will need to visit a gynecologist for thorough examination, vaginal smear and culture test and a PAP smear along with ultrasound scan to see what could be the underlying cause.
Take care.