I had the Mirena coil fitted in April 2015 due to heavy / flooding periods. Since having it fitted I had continual spot bleeding, where I only had around four days with no bleeding at all, I was unable to tell when my period was due, if it had been at all due to the constant bleeding.3 weeks ago what i thought was my period for 4 days then continued where I had excessive blood loss (changing pads every 1-2 hours) with flooding followed by huge blood clots (about the size of a digestive biscuit).The blood loss has been on going for 2 1/2 weeks. Doctor has given me steroid to stop the bleeding. Internal unsuccessful due to excessive blood so couldn t see if coil still there. Pregnancy test negative. What has caused this?