Is Pregnancy Possible If There Is Menstruation After Intercourse?

hi my names ashley and i need answers please well i had sex with this guy 4 months ago and me and my bf the bf i have now we broke up while i was talking to this other guy and we had sex and i didnt know he cam inside me but his cum was smelly and really runny and a week later i got my period could i be pregnant if i started my period after him?