What causes costochondritis because I have shortness of breath chest pain upper and middle back and sometimes my neck?

Costochondritis. Costochondritis is usually a localized inflammation of a joint between a rib and the sternum(breastbone) and causes pain and tenderness in that localized area. If you're having Sharp rib cage pain, worsened by a deep breath and radiating around the side to the back, a pinched nerve which runs between two ribs is suspected. In view of your shortness of breath, an exam is indicated.