What Causes Brownish Discharge During Menstruation?

Hi, may I answer your health queries right now ? Please type your query here...I am 40 yrs old and have always had normal periods, no problems and no abnormal paps. Last month I started a week early at 21 days but I had been under a lot of stress and do that from time to time and it was a normal period. However ever since that I have had a brownish black discharge, nothing real heavy but it is now time for my next period and I am still having it. Now it is a little more like I am trying to start and it is about my 24th day. U think I need to go to the DR? Thank u