If it's not too bad it's probably ligament pain, but a couple weeks ago I had really sharp pains in my lower abdomen and it ended up being a urinary tract infection, but if the pains aren't really bad and just uncomfortable I wouldn't worry about it
I get a lot of aches and pains on both sides sometimes up the middle too. My doc told me that its just the ligaments stretching and that its normal, unless it becomes crampy or extremely painful. There are so many weird things that happen to your body while your pregnant its hard to know whats normal and whats not!