Sex Drive

I feel like I lost my sex drive. I'm two weeks late on my period but the two tests said negative. I've always had a high sex drive, like I'd attack him. Anyway last night I just couldn't get into it. I just wanted to tell him to stop but I let him finish. I have no desire or want to have sex anymore. And it makes me sad because I really love sex. It may because I missed my period and my hormones I don't know. I'm just not used to it.