Period Nonstop

Abigail
I've been on Implanon (the arm implant) since June 2016 and haven't had my period since then, except for the past two weeks which I have been bleeding non stop. Any advice? They said to give it a year to see if I like it, but I'm not sure when I should go to the doctor about this. I'm used to spotting with my implant but not bleeding this much! Help please!