What causes a man a sharp pain in my upper back on the right side?

Several poss. causes: Some causes are more serious than others, but usually, if the pain is sharp, it indicates a musculoskeletal problem. Such 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.

Lots of things: Most common back pain sources are strained/pulled muscles but "sharp" pain into the shoulders and arms/legs can be from a herniated disc causing nerve compression. If the pain comes around your chest/abdomen from the back this can also be a disc herniation. If you're having any neurologic problems (like weakness, etc), or the pain persists/worsens, you need to get this evaluated by a specialist.