Why I am feeling Dizziness and vomiting?

I had sex with my boyfriend after 11 days of my regular period. My Last person was last month 23rd and exactly 1 and half week later my boyfriend and I had unprotected sex. Feeling guilty about it but anyway I took plan b one-step right after like one hours or 30 min later. I mean the same day, I feel normal for a week but suddenly I start feeling dizziness and little vomiting. I am very scared BC i took first time plan b one-step. we had sex many times but every-time he didn't came in.... so do this time but I never took plan b before but this time to be on safe side I took plan b one-step. please answer me is there any chance getting pregnant? I am also not feel like eating sometime too, and sometime I don't even for a days or two I eat junk food drink, like Candy, or Starbucks etc.. Even now I feel my stomach hurt my boobs little sour sometime and my back hurts too... please very simple answer.