Thanks for writing to us.
From the description, it seems you might be suffering from Costochondritis
The causes are not exactly known for this condition, but certain things trigger costochondritis. These include a blow to the sternum/or rib area, an infection in the costochondral joints, perhaps caused by a surgery, and overuse of the muscles and joints surrounding the sternum.
Visit the doctor. Your doctor will be better able to diagnose costochondritis.
Wishing you good health...
Dr Saurabh Gupta.