25yo chest pain and upper back pain doctor thinks it's muscleoskeletal. 3ekgs and blood work all normal. how long can muscleoskeletal pain last?

Physical therapy: In a young person without any medical problems, the most likely explanation is musculoskeletal pain. This in particular if there is any history of injury or excessive strain or use of the upper body muscles. If the discomfort improves with heat/massage/nonsteroidal anti-inflammatory agents-this also points towards musculoskeletal strain. Often physical therapy may help with the symptoms.