What Causes Vaginal Spotting And Sore Breasts Post Having Unprotected Sex?

I had unprotected sex on the feb 7th and have kept having unprotected sex on the feb 27 I had unprotected sex again but straight after sex I started spotted light pink red blood wasn t much though what does this mean? I ve been getting sore itchy boobs aswell bit of belly pain and feeling a little sick? I have irregular periods aswell? I had my last period the same day I had sex on feb 7th after having sex then come off on Friday 13th I haven t had a period since and dunno when I should come on? Could I be pregnant what should I do?