Mirena coil

I have been taking tamoxifen since 2015. I have not had a period for 2 years. I was diagnosed with a polyp after a heavy bleed in December 2017. I had this removed 12th Feb. 2018 and a mirena coil fitted. I was unsure about this at the time and now have a funny feeling I shouldn’t have let them do this. I have been bleeding for 9 days now.