Bleeding after Sex ??

this isn't my first time having sex. I have sex plenty of times with my ex boyfriend. Now I have a new guy and we just had sex . I haven't had sex for a year up until today. Anyways, so when we finished, I went to the bathroom and it wasn't just spotting, it was allot of blood. I had JUST ended my period the day before. So I don't know if it was period or something else. Please make this make sense. cause I would be embarrassed if I had started my period while we were having sex. ( we had sex in his car btw )