Levonorgestrel
"Just got it inserted yesterday, it was probably the worst pain I have ever experienced.  I wasn't warned to take any pain prevention medication, so it was probably worse than normal. I have had pain and cramps all day. I was spotting before I got it inserted, and yesterday it got kind of worse but today it has lightened. I am hoping that it is not like the implanon where I had my period for a month at a time."