What Cause Abrupt Stopping Of Blood Flow After Having Sex During Menses?

hi i had sex with my partner on the first day of my period. he dint come inside me, we did it on the second day also we made sure he did not come inside me on that day too. my period suddenly stopped after the second day i am worried because i usually bleed for 5 days heavily and it stoppped in just two days.so i took a emergency contraceptive pill on the third day evening, i still am not bleeding. could i be pregnant