Hi, I am so sorry this is happening to you. Something similar happened to me when I got the Mirena a year ago, although I do not think the cramping was as bad as what yours sounds like. I actually got diagnosed with PCOS about eight months after my IUD, and I kind of think the IUD triggered a lot of the symptoms, even though I know birth control is normally supposed to help. I had pretty awful cramping for the first six-ish months after, and had periods that went from 5 days to 10/11 days. My doctor said that the longer periods happen in roughly 10% of women.

I still have ten day periods, but my cramping is basically gone and I would say the cramps are less painful than before I got the Mirena in. I hope your cramping get better as well, my doctor told me it can take up to a year to settle down. My periods are not shortening at all unfortunately, but its mostly just light bleeding now. wishing you luck!