What causes sharp chest pain between the breast?

A sharp, especially sudden& fleeting chest pain is rarely caused by cardiac or lung problems but is more apt to be of musculoskeletal origin or caused by a pinched intercostal nerve or muscle that runs between 2 ribs or by inflammation/ irritation of a joint between a rib and the breastbone. A deep breath often precipitates these sharp chest pains. See your MD for evaluation as needed.