PLEASE HELP!!!!!

Hey y’all so I have had TWO periods in one month and I have been on Nexplanon for about 2 years now. Not only that two periods but this time I got some really really bad cramps. Were all I want to do is cry! My boyfriend and I have had sex about 5 times in the span of 4 days and every time he has finished in me. (TMI but we had sex while on my period). I just want to know why the heck I am cramping so so bad!!!!!