What Could Itchy Brown Vaginal Discharge Suggest?

hi! just lately a week ago I went to my doctor because i have brown vaginal discharge, it is not smelly and it is not itchy but my left lower part of abdomen has a slight pain with my left back part of waist. I have this discharge for two weeks after my period then she prescribed me canesten 1 tablet after i took the medication the discharge color was change into pinkish but with the stuff from the medicine. after 4 days the discharge is still there but it come back to brown..but before it turn out to brown some sticky watery came out....