I have brown vaginal discharge today. my period ended sunday night. i am not sexually active, and this has never happened before. what could it be?

Normal.: While some women have menstrual cycles that are identical from month to month, as you get into your late 30's, your ovaries are not as consistent. What this means is that there could be a subtle hormonal imblance that prevented a thorough shedding of the endometrium. The brown discharge is very common and nothing to be concerned about.