Implanon Birthcontrol/New name Explanon. I got it inserted on September 13th so it's been two weeks basically. I was suppose to start my period that day of insertion or days following and I STILL havent started. I have crampy achy feelings like I'm going to start but I still haven't. Is this normal?? Has anyone else experienced this?? i know it can make you not have a period at all but that fast?? Some help me out.