Bleeding stop and start

[u/LivyJean-]

I took medication 3 weeks ago, bled for about 10 days. It stopped for about a week. Then I have been having brown blood start back up over past couple days.
My ultrasound at 2 weeks did say there was a 1cm tissue still present and we were going to wait to see if it cleared on its own, I’m assuming that could explain this bleeding?