Upper back pain can have a variety of causes.
Infection of the lungs can cause acute pain but often muscular imbalance can be the reason for long term pain such as yours.
If you have strong chest muscles but weak upper back muscles the back muscles can be pulled as the shoulders become rounded forward.
Try some 'butterfly' extensions. These are easy to do at home:
- bend forward and support your weight on the arm of a chair and lift a weight from near the floor to beside the chest with the other arm.
Repeat 20 times and swap sides.
This strengthens the upper back muscles and you should aim to do 3 sets of 20 to begin with, every other day.
While you have the pain, though, please try our Arnica Gel ("Atrogel®"). It should offer some relief.
Another remedy I would suggest is magnesium, about 300-400mg a day. Magnesium helps relax muscles.
I hope this all helps.