Do I have possibilities of being pregnant?

Hello i have a question... in my last period at the 2nd day I had unprotected sex with my boyfriend, my period is very regular so we thought that nothing is going to happen, I mean we think there weren’t pregnant possibilities. My period is in a week and I have a lot of pain at the ovaries and boobs, and i feel so dizzy and exhausted... it is the first time this happens to me.