Nexplanon

So I got my nexplanon about 4 days ago. I’ve never really had cramps before cus my periods haven’t ever been bad but I think I’m cramping some. Is that pretty common four days in?? I don’t think there’s anyway I could be pregnant cus I had a period last week and haven’t had sex since before my period. Is it probably just my nexplanon causing the cramping. It’s not bad. Just annoying and noticeable