I am 25 years old and it's been about 13 months now since I've had the Implanon inserted. I have never had my period since it has been inserted. Other symptoms in the months following insertion included migraine headaches, nausea, and mood swings. After about 6-7 months of having the implanon, the side effects began to subside a little, up until a couple of weeks ago when I started experiencing extremely sore breast (currently still sore) along with some cramping and lower backaches. What could this be? please reply. Thanks for your help.