I have upper back pain for about 10 years after lifting a heavy weight. Please help.

Hello doctor,

I am a 28-year-old male with no medical disease. 10 years ago, I lifted a heavyweight and I felt upper back pain 6/10 in severity. With time it is associated with shortness of breath. When I stay in a chair for a long time, I feel upper back pain and shortness of breath. When back pain is reduced, breathing gets better. I visited a GP (general practitioner) and all investigations are normal. He referred me to an internal medicine specialist and again everything is normal. X-rays of the spine and chest are normal. All blood tests and EKG (electrocardiogram) were done and are normal. The pain is very minimal in-between if I do any work it might increase but it is continuously there for 10 years and also the breathing is affected. No psychiatric disease, no panic attacks, or anxiety. I only have back pain and shortness of breath which I cannot take a deep breath, but I can walk, run, etc. I think I have some muscle or maybe a disc problem that causing pain but I am not sure what exactly it is. I did not try any physiotherapy before.