Hello,
Brown discharge could mean that for whatever reason during your last menses the entire uterine lining failed to make a timely exit. If you have not had intercourse, then chances of pregnancy are less. But you should check up with a gynaecologist to rule out any vaginal infection or abnormality. The normal vaginal discharge is not foul smell and usually clear or milky. There are certain things that may cause change in appearance of vaginal discharge are like menstrual cycle, ovulation, emotional stress, use of pills or diet.
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.