Anal Sex/ Missed Period

So I have had anal sex almost every weekend for the past month with the same guy (we are both only done sexual things with each other so don't think this is STD related). Anyway, I am 12 days late on my period but I'm still experiencing cramps and nausea and everything, but I didn't know if maybe anal sex was related to my missed period? I have had a regular period since I had my first period 10ish years ago. I just don't know if any one knows anything about this or has had experience with it.