Was this my period? What else could it be?

So my period is expected to start in 2 days. I was at this dude's place last night n during sex, I notice that there was a lot of blood on the sheets. So I figured my period had started n I used a tampon. However, I'm not bleeding now. Not even a little. Thus indicating I'm not on my period. I don't understand why I bled so much? I've been sexually active for 5+ years now. Does anyone know what might be the reason for the bleeding? Fyi I can't ask a gynecologist coz premarital sex is illegal here.