I Am 43 Years Old. I Have An IUCD. In

I am 43 years old. I have an IUCD. In the last 1 year, 8 months I had less bleeding. But from the 9th month I started getting more bleeding with severe pain. I checked my Mirena. Its in place. I checked my uterus. Other than a small cyst in right ovary, everything seems normal. But I am suffering from severe abdominal pain everyday with either small clots or little bleeding. Why I am suffereing from severe pain? What is the cause for this pain? My gynic is also surprised with this pain. She says my Mirena may be failing.
Kindly help.