HELPP!!

ka
I just had sex for the first time 2 days ago and when i got home after having sex i was bleeding a little when i got home and then when i woke up there was a little blood in my underwear but i didn't think it was anything to worry about until the next day my discharge was brown reddish like i just got my period but my sugar pills aren't until another three weeks so it's not my period, is it anything serious?