My son is 14yrs old, and sometimes he gets a sharp pain in the upper left side of his chest, it feels like if something is putting pressure.

Precordial Catch: Precordial catch syndrome (pcs), also known as texidor's twinge, is a common cause of chest pain complaints in children and adolescents. It also occurs, though less frequently, in adults. Pcs manifests itself as a very intense, sharp pain, typically at the left side of the chest, generally in the cartilage between the bones of the sternum and rib cage, which is worse when taking breaths.