Sounds like contractions. If they are irregular, it's not true labor. If the become regular and have 6 with in an hour, call your Dr or go to L&D
If they are lower in your abdomen could be contractions however if they are higher in your chest and back it may be gallstones. I have had gallstones since early on in my pregnancy and they have only bothered me a few times but when they do they HURT. The doctor wants to schedule to have my gallbladder removed after my daughter is born.