What Does Spotting Of Black Blood Indicate?

i'm a virgin
i was with my bf on Thursday night we were playing and my Virgina was close to his penis got my orgasm
and my bf i think he got his pre-cum although he said he toke a leak before meeting up with me and on Sunday i had all my period signs cause i was couple of days before my period so i started spotting black blood for one hour then it all stopped and now is Monday and there is no period what could have gone wrong