Is there any bleeding? If there's any bleeding, get to the docs asap. If not, have you lifted anything heavy? It could also just be the baby setling as your body widens to make room for this child to grow. If you are really worried and the pain does not go away, go to the doc's. I remmeber getting pains inthe begining too and kept thinking miscarriage as I had had 2 previously, but it was nothing. It was just my body adjusting to make room.
Like I said if you get really worried go to the docs. It's prob nothing. Lol this is my first and i'm 36 weeks and can barely remember anything from the 1st and 2nd tri. You could have just slept wrong too. If you start bleeding go to the doc's but you can call them too just to be on the safe side as i'm no doc. Good luck.