Leaning forward pain in right breast and sternum. then bending over pain through left breast and chest to back.doc says heart ok. muscular?nerve?gas?

Positional: The positional nature of your pain makes me wonder about your spine - as you lean, you flex and extend it which open and close your neural foramina (the canals where the nerve roots exit). Arthritic spurs often encroach on these canals and can cause nerve root irritation. Arthritis in the facet joints of the spine can further cause positional pain.