What does it mean when I have a little bleeding after I had

I started my period on May 17, and it ended on the 24th. While I was off my period on Tuesday (May 27), my boyfriend& I had sex. The next day (May 28) when I woke up I noticed some bleeding. I didn't think it was really anything big, but now it's already been 6 days and it hasn't stopped. It's gotten to be a brown now. What does this mean? Am I pregnant?