Can i get pregnant even after using condoms??

hi...m dam confused n in need of ur advices!!..actually dis 31st,i and my boi frn decided 2 stay 2gethr..n although unintentionally,v landed up havin ...he used condoms..bt sumwer in my mind i feel dat m pregnant cuz dis daes my tummy aches a lil..m still not sure n confused n scared 2..what do i do nw?plz help me!! Shelja