Levonorgestrel
"I had this IUD for about 5 months. I experienced the worst cramping of my life with this IUD, at times nearly bringing me to tears. I would have cramping with things like working out and after intercourse, and also at random times. These cramps were completely debilitating. I also continued to have my period every month, as well as spotting. It seemed as though the spotting was starting to get better, but the intense, severe cramping persisted so my GYN agreed that it should be removed. Now I'm trying mini pills. I'm unable to use estrogen containing birth control due to a blood clot while on combo pill."