What Causes Heavy Menstruation With Clots And Bleeding Odor?

I had a baby 7 months ago and after birth I bled for 3 months straight it stopped for one week and then restarted. I now have periods lasting 2-3 weeks with the first 2-3 days being very heavy foul smelling bleeding through super plus tampons every one to two hours with large clots sometimes golf ball size passing. It then becomes a yellow urine color with gray to black foul smelling discharge for the remainder of the time.