What to do for Abnormal Rib Cage?

For as long as I can remember my left rib cage has always been larger than the other. There is a small piece (quarter/half dollar size) on the lower end of my left rib cage that sticks out. The problem is that it tends to hurt every now & then. I sometimes sleep on my side at night & sometimes I can't do that because it is uncomfortable. Also, there is a smaller area (dime size) on the part of the rib cage that sticks out that if I push on it moves. Lately when I breathe I can feel it rub on something that creates an uncomfortable feeling as well. I know this sounds weird but, if you can inform me about what it could be I would appreciate it!!