What Causes Vaginal Bleeding After Removing Mirena Coil?

I had mirena coil removed after seven weeks due to irregular bleeding and watery discharge. I started microgynon seven days before having it removed. At the time I had it removed the bleeding had pretty much stopped. On the day of removal I had a heavy period for a week. It is now much lighter and darker but still bleeding after 2 and a half weeks removal. when will it stop