Hello,
I am 22, and until now have always had a fairly normal menstrual cycle. I am in a monogamous relationship, and although I am no longer on birth control, we always use a condom.
Sometimes (although not everytime), I've had some spotting during sex. (I have no idea what the cause of this is.) The other night, this happened... but then it basically turned out to be my period. This wouldn't be strange except that if it is in fact my period, it is almost 2 weeks early!!