Can having sex for the first time in a while cause you to get your period?

I had sex for the first time in 7 months on Thursday. I have been on the pill for two years and we used a condom as well so I know this isn't a pregnancy thing. But suddenly since yesterday I have been bleeding as if I am having a period but on my birth control I am not due to get my period for another two weeks. Could it because I had sex?