Pregnant or not? please help!

Patient: I and my girl friend had unprotected sex after 5 days since her periods ended. then she took ipill within 1 hour and then had periods after 5 days of taking ipill. she usually gets on her periods on the 12th but this time due to aking ipill, she even had one period on 26th(the one that took place after 5 days of taking ipill) . now in the next month, its 13th and she is still not on periods and was feeling a little nauseic and even vomitted but we reckon that it was cause of food poisonng.can she be pregnant?