Brown vaginal discharge is most often associated with old endometrial tissues. In other words, if your period is late you might get a brown, rather than red, discharge. It could also mean that for whatever reason during your last menses the entire uterine lining failed to make a timely exit. In some cases however there is cause for concern like cervical cancer, pelvic Inflammatory Disease (PID), menopause, or sexually transmitted diseases like gonorrhea and Chlamydia .You should consult a gynecologist who will physically examine the local area and may consider tests.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.