Sudden constant period from Implanon. I'm 17 and I've had the Implanon implant for nearly two years now and for most of the duration my periods stopped. A couple of months ago I had a dark brown/red clot-like period which has been on and off constantly up until now. Very worried since I've never had anything like this before and haven't had an STD test for about a year, could this be a correlation?