What can cause upper back pain when i breathe?

A few things: Serious problems such as pleurisy are possible.In my practice, most such pain is due to a malfunctioning rib.Ribs should 'go up' in front and 'down' in back with inhalation and do the opposite during exhalation.When one or more ribs 'get stuck,' pain-from ache to severe sharp in front &/or back can occur.A good history & osteopathic hands-on exam could determine cause.Manipulation may fix it.