What Causes Sharp Pain In Lung Area?

This morning, I noticed a sharp pain in my right lung area. It is a sharp pain, it varies in intensity, and worsens at the deepest part of a breath intake. When I sit up extra-straight it seems to lessen for a moment, then resumes. Two days ago I hit my head suddenly on an unseen overhead obstruction. Is it possible I pulled something in my chest that is just aggravated?