What Causes Heavy Bleeding,feel Of Lumps In Breast And Back Pain After Having Implanon?

I have had the implanon birth control for about 2 years now, the first couple of months, I had taken birth control pills to help stop my period that my doctor had prescribed me, while the implanon was still in my arm. It worked and my period stopped, the first year I had no problems, about half way in to my second year I started to lightly spot, but I wasn t concerned. Now I m on my second year and I am bleeding extremely heavy, my brest feel lumpy and they hurt really bad. I have horrible cramps in my lower stomach and my back hurts every now and again. Ive been reading a lot online and itseems to say that I could be pregnant. I am sexually active, and have been for the 2 years ive had it.