Make sure you keep you ob in the loop the whole time. Could be anything from usual practice contractions to the REAL thing. I had the same thing happen and it was preterm labor but my cousin said it felt the same and it was just Braxton hicks.
It's just your body preparing for labor. I always get them the last month before the baby comes. Now if they get stronger or more consistent start tracking them. Everyone is different but my contractions in the beginning of labor always just felt like really bad cramps.