My 13 year old son has been having chest pains and shortness of breath on and off for over a year, so we took him to the cardiologist to be checked out. His heart is fine. Apparently there's a condition some people have when their interior chest wall isn't completely smooth, like during a growth spurt, and when the lung expands, it gets caught up on a rough spot and hurts, giving you chest pains and shortness of breath. He just has to take shallow breaths till it passes. Most people outgrow it. It's a relief to know it's nothing serious.