unprotected sex on the pill

so, me and my boyfriend had unprotected sex just this past tuesday, right after my tummy started to really hurt and same with my boobs and back, i’ve been on birth control for three weeks now, i am now starting the sugar pills. i do usually have these symptoms before my period but i’m just wondering, should i be worried?? he didn’t cum at all and i’ve only missed two pills, also i read you can’t have any pregnancy symptoms til later on. i’ve also had brown discharge, which i usually get before my period, pls comment down opinions, i’m really freaked out. i had sex on my third week of taking the pills, i haven’t taken any plan b.