My boyfriend and i were together on tuesday. he cummed on my underwear (on my *** portion). i’m scared that i might become pregnant?

i had class, and i still wore the underwears i had on that he cummed on and i’m really really scared that i might become pregnant or anything/: someone help please.. today i had a huge pain in my stomach in the middle and i thought it might be cramps that i’m going to get my period but i’m not sure really