What can cause upper back pain?

Many causes: Cardiac causes including valvular or coronary heart disease, angina, throracic or addominl aneuryms, thoracic masses intrathoracic or extra thoracic, bulging/herniated thoracic or cervical discs, muscle spasms , clavicle fractures, referred shoulder or neck problems, pulmonary edema, luminary embolus, vertebral fractures or masses, post surgical scar tissues, beast rumors, arthritis of spine.

Additional thoughts: This was answered very well by dr. M. Sacher. I'd like to add, however, that much benign back pain can be caused by malfunctioning vertebrae or ribs, spasms, or pinched nerves. A good history & physical exam, including an osteopathic hands-on exam can often find such problems which can be easily correct by manipulation.

Multiple: There are multiple potential sources including musculoskeletal or referred pain. It is best to see a medical doctor.

Many Possibilities: Given that this has been going on for so long, i would consider an evaluation by a spine specialist. Sometimes it could be a muscle imbalance, early onset arthritis or scoliosis. Also could be a pinched nerve/herniated disc. Either way it might be good to figure it out and get appropriate treatment.