Just Birth Control or something else?

Last month I stopped Birth Control. I got my period April 16th-22nd and from April 22nd to May 2nd I had unprotected sex every second day. I got my period again on CD34(May 20th-25th) I had sore boobs before my period and it went away after. I just started Birth Control again and I'm on my 5th pill today. I have sore breasts and nipples,I feel nauseous in the mornings and through out the day but I don't throw up. Im getting dizzy spells with that. Is it just my birth control?