I have sharp pains in upper back?

Depends on your age: If you are young and otherwise healthy, or even if you are older, this could be a "pinched nerve." if you smoke it begins to get more complicated. If it interferes with your quality of life your spine will need to be imaged and you will need an exam of the nerve function in your arms.

Its possible: You may have sharp pains in your upper back. There can be many reasons for pain. This can be a primary back problem or stress, ulcer, or overuse. A little bit more information is needed here. Is is achey, sharp, or throbbing? What is it accompanied by? What makes it better or worse?

Unclear: It could be muscle spasm. I suggest being seen by your pcp.