Been having dark brown/reddish brown discharge for 12 days now. it started march 7 and i was supposed to get my period on march 12. wht could this be?

See below: If you normally have regular cycles, and now essentially did not get a normal period and are having daily abnormal bleeding, the first thing you need to do is to check a pregnancy test. If this is negative, then it is possible that this bleeding is related to breakthrough bleeding after a cycle where you did not ovulate. This is a great reason to see your doctor for options for cycle regulation.