TMI BEWARE!!!!

Ok so I need some help! This has never happened to me before and I would like to know what can it be, if you have any idea. I had unprotected sex 2 weeks ago when I was ovulating, but he didn't cum inside me (I know you can get pregnant by pre ejaculation). This week I got my period (if I can say I did). Well Monday I was getting cramps and usually I get them like a week before my period starts. My breast hurt also which was weird because they never do, so I thought I was getting my period. Nope I just had brown spotting. Tuesday came I thought I got my period which only lasted that day. Wednesday I had nothing it stopped completely. Thursday and today Friday I was spotting light pink.