hey i have been getting the same thing and have found out my pelvis has tilted just a lil cause of the weight with the baby, my hospital referred me to an inhouse physio which has showed me some exercises.. i also have to wear a belt and a tummy support band which helps your muscles support the extra weight believe me i know the pain i cop it everyday without fail and sometimes it feels like someone has corked my sides and i try and walk it out but it kills maybe see on your next appointment what they can do for you