I Had An Abdominal Myomectomy A Year Ago. Five Months

I had an abdominal myomectomy a year ago. Five months prior to that, i had a uterine ablation done and then there was one fibroid they had missed. Everything has been awesome since then. For most of the year, I have had little to no menstruation. In the past five weeks, I have been bleeding three separate times. The second time (two weeks ago) it was heavy at times like the clotting I used to pass before the procedure. Today I have been having dark brown discharge and it is getting heavier as the night goes on...any ideas about why or how?