Hello...i had unprotected sex with my girlfriend and i cum in her,she had her periods

on 2nd of July to 7th and on 13th July we had sex.then 5 days after sex she told me 

her abdomen is itching and on saturday which was on 20th she took postinor 2 am really confused

because she can be pregnant and she took the pills will it help her.please help.i have posted this 

question twice but can't see it.help please.