Could be break through bleeding I'd take a test if you didn't use protection or see your doc
It could mean a few different things I would wait until around the fourth of the next month and take a pregnacy test it sounds like it could be implatation bleeding. I don't know much about that since I never had with any of my pregnacy. It also could be just your cycle being funny or you could have an infection if it keeps up I would make a doctors appt.
Good Luck
Misty