I've had the Mirena for a little over a month now. I had excruciating cramps for the first 2 weeks and have been spotting/bleeding everyday since it was put in. I couldn't find the strings anymore, after being able to for the first 2 weeks.
I went back to my doctor and she couldn't find it either so I have an ultrasound tomorrow to find it. Ironically, the majority of the cramps stopped at the same time I couldn't find the strings. I don't know what's going on with it.