period after plan b, please help!

Yo
hey so please don't judge but i had unprotected sex about a week ago (two days after my period ended), we were pretty drunk and i didn't even realise he wasn't using one...anyways he came on my back but i still didn't know if any got in me and if he pulled out at the right time. so in the morning i took plan b (i've never had it before) literally i've been having mild cramps ever since and last night i had brown discharge, this morning i got my period...idk what's happening i literally had my last period about a  week ago and now another one. please help idk what's happening and i'm worried if there is a chance of pregnancy! 😩