Sudden heavy bleeding after 3 years of no period

Hi, so I'm hoping someone can save me a trip to the doctors and give me some sound advice... I had the implanon inserted approx. one year ago. Before then I had been on the Depo Provera Injection. For the last 3 years I haven't had a period, at all. Last weekend I started bleeding very heavily, more than what my periods used to be, and I was always on the heavy side. The blood is very dark, stringy. I haven't had any cramps, nothing to warn me that it was about to start. It lasted for about 3 1/2 days, then suddenly stopped. Yesterday it started again, same thing, really heavy, dark and stringy. No cramping. I feel rather lightheaded and weak, probably because my body isn't used to losing this much blood over a short time! :) . I'm about ready to go to the doctor and have the implanon removed, as the feedback I've read so far has been rather negative and it sounds like this could continue. Because I hadn't had a cycle in so long, the doctors inserted it straight away without knowing where in my cycle I was. I'm wondering if it would work for me to have the implanon removed, leave it for a couple of months and just use condoms, and then have a new one inserted.? Does anyone have any advice as to what could be causing the sudden bleeding after such a long time of not having periods? When I was talking to the Dr just before having it inserted about not having periods on the Injection, he told me it would be highly unlikely for me to have a period on the Implanon as they both consisted of the same hormones etc. I'm very nervous and wondering if this means the implanon has been moved and isn't working properly, or something of the like. Any advice would be greatly appreciated, though I have a feeling that by the time I recieve a response, I've probably already gone to the Dr's. This much blood freaks me out :) Thanks for your time, and thanks in advance for any responses.