From what you are describing with the pain in the upper back localized around the shoulder blade points to an anatomic abnormality. One possible explanation is a glenoid-labrial cyst that has arisen from a past shoulder injury such as a torn labrum. These cysts are comprised of synovial fluid and cause irritation, inflammation, and pain. Another explanation is a pathologic process involving the lung. Deep inspiration and twisting in a certain direction can cause pain.
You should be evaluated by your doctor to determine the cause of the pain. A chest and shoulder X-ray is warranted to initially evaluate any lung or shoulder abnormality. If the X-ray is inconclusive, then an MRI may be performed to evaluate the shoulder in detail. Alternatively, if your doctor believes your pain is due to a lung disorder, then a CT scan of the chest is the next best test.
