Levonorgestrel
"I got Skyla inserted almost a month ago. My cramps and lower back pain were bad for a few days, and 1600 mg ibuprofen daily didn't help much. (My periods are usually heavy and painful; I had vaginal delivery without anesthesia. The pain from the Skyla could be compared to my worst period cramping.) By the end of the first week they became tolerable, but I was still spotting. There were 2 or 3 days when I didn't spot, then I started having bad cramps again + spotting, and a long and painful period followed that was a little lighter than usual.
Well, I'm still spotting/bleeding and having cramps and obviously not pregnant because I have no mood when I'm in constant pain.
I'm willing to give this method another 2 months..."