Any other mommy's have the Mirnia IUD. I have had it since June and my periods have been liter and…

Any other mommy's have the Mirnia IUD. I have had it since June and my periods have been liter and no pain at all. This time around I am having really bad blood clots and lots and lots of pain and bleeding. I just the strings check and my yearly so I know it's still in place and all but why is it like this this month when it's been working so great until now