Implanon - period symptoms, no blood.

Courtney
Hi all, 
I've had my Implanon for over 7 months now and it's been fantastic.
I was experiencing my period for over 2.5 months and took the progesterone pill to supplement the implanon. My last period from memory was February. However, I'm 80-something days late on my period and today I experienced period-like cramps but they weren't immensely painful, like they used to be with me. I also noticed a little bit of murky brown discharge once today.
Plausible explanations as to what this could be?