I need serious help !?

Im 17. I happened to have unprotected sex with my boyfriend during my periods twice on two alternate days and had an i pill each time.This happened in the 1st week of june. Since the past three to four days I'm not been keeping well. Everytime I eat something it makes me sick and nauseous. I don't vomit though and I just get burps. Yesterday I could not pass stool and today in the morning I got loose motions. I'm also having a terrible headache. Is there a possibility Im pregnant? WHAT SHOULD I DO ? I discussed with my boyfriend who I've been with for the past 3 years and he seemed stressed but he said we'll manage if something happens. Hes 23. Im really worried !! please help !