Hiya, I had the exact same thing happen to me after having the implant for two years without any problems. I bled for around 12 weeks non-stop and like you I was very worried. I went to the Dr who said that the implant can cause irregular bleeding throughout its use even if it hasn't caused problems earlier on. I decided to have the implant removed and switched to the combination pill. After the first 1 week break from the pill for my period everything went back to normal. Hope this helps x