tmi probably but please help

Okay so the past two days I've had quite a bit of discharge, but it's not normal discharge feud fit was like a brownish grey, then it was a brownish with a little blood, then it was just brown now it's mainly like a really dark dark brown it almost looks black and sometimes it's dark with blood. 
Few side notes: I'm in nexplanon - got it dec. 13 2016 - started my last period on dec. 12 2016 and ended on dec. 17 2016 - I don't know if it would have anything to do with it but my boyfriend has "finnished" in me 2 or 3 times but it was after the two weeks that they told me. I hope that covers all my bases