Could I be ?

Ok so I had protected sex on 3/14/16 and started my period on 3/28/16. We haven't had sex since then except fingering and blowjobs. And my expected date of period was the 29 of this month but I've been getting really bad cramps so I went to the bathroom at school and saw this really brown stuff on my underwear and I'm freaking out could I be pregnant? Or did I catch my period early?