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It is probably costochondritis
(inflammation of the rib / cartilage
Relation to movement and posture negate relation to heart and lung...
The limited information provided is not sufficient enough to arrive at an appropriate conclusion and further suggestion... / You have not stated your personal habits, family history, or co-morbidities, even age or gender...which could influence the diagnosis and outcome...
The wise option is to get yourself examined / can’t you go to ER?
Wishing speedy recovery