it could possibly be your bubba putting pressure on your rib cage....with a little foot or knee

the rib cage does expand in pregnancy...but babies have a unique ability to get right under the ribs and 'tickle' our diaphragm, which causes that sharp, painful sensation. Some women feel it as referred pain in the back, just under the shoulder blades

reflexology or osteopathy help as they both work on aligning the skeletal system

positions are also useful...such as yoga
try sitting on the floor in front of a chair, with your knees wide (wider than your hips), big toes together and sitting with your bum on your heals...then keeping your bum on your heals bring your folded forearms to the seat of the chair and rest the head down
this is a great stretch for helping relieve pressure on the rib cage and diaphragm, and helps to alleviate heartburn and breathlessness
resting your forehead also calms the nervous system...reducing BP and increase feelings of wellbeing and relaxation

xx yogababy