Effect of ipill on periods? she is having abdominal pain and her period is late

I have unprotected sex with my gf on 16th march, but i have not ejaculate in her, but still for safer side she took ipill after 48 hours, her period dates is on 28 march, and since last 4 days she is having abdominal pain and wamiting and till today she is not having periods, So is this a cause of pregnancy? Please assist me