I strongly recommend that you consult a physician. An orthopedist, a cardiologist, pneumologist or even a plastic surgeon. This condition is not only aesthetic, you know? It can affect your respiratory and cardiac functions, your posture and therefore your spine, and several other serious conditions, such as diaphragmatic hernia, neurofibromatosis, cerebral paralysis, Poland syndrome, Marfan syndrome, Prune Belly syndrome, and several others.
It is treatable, even without surgery depending of the case
. So go and consult a doctor and get that thing fixed!