What tests would best determine the cause of upper back pain, with should pain also? where would you go for those tests?

First step first: I am not sure what is the nature of your pain (when does it occur, left vs right or mid, during day/night, at rest, when active, or both), and how long you have had this pain. Also, any trauma? Type of work you do? First and right thing to do is consult with your doc for a thorough history and physical examination, which maybe all u need, and work-up if needed. Motrin/aleve for now. Good luck.

Physical exam: Palpation of trigger points i find MRI of the thoracic spine to be a waste of time and money for evaluating upper back pain with tenderness unless you have a past history of cancer or trauma historyor pain rhat radiates in band like fashion around to front only reasons to get one . Pain with tenderness just chronic muscula treatable disc abnormalities in the nonmovable part of spone rare abide.