Hi,
After having 3 very big baby boys I totally sympathize! What happens is everything in your body expands including your ligaments which attach muscle to muscle. This pulling can cause discomfort and sometimes pangs or shooting pains.
Some solutions are to get pre-natal massage from only a liscensed massage therapist because they are trained and know what is contraindicated for pregnant clients. Using a pregnancy pillow can help as well while you are sleeping. This helps to keep your spine in alignment. Make sure to take any vitamins your health care professional prescribes.
Remember that this will not last for ever and soon you will have a beautiful baby!!
Wendy