Nexplanon HELP!!!

Kelsey
I've been on Nexplanon since the first of December! I was not constantly bleeding at first but I would have brown discharge and sometimes a period off and on. I haven't had any discharge and my period hasn't came in over a month. Sexually active so I took two test yesterday and both came out negative. I have awful headaches/migraines, and cramping and I'm exhausted all the time. Has anyone else had these symptoms??