help!?

i might sound dumb asking this but o well..okey so me and my bf just had sex but i was on my period we both dont like doing it when im on it but we really had it going on this time that we couldn't resist it was my first time doing it while i was on my period well my question here is it bad to have sex while on ur period because i feel something stuck inside my vagina idk if its all the blood but i heard it was bad and im kinda freaking out right now plz help.?!