Why does it hurt to breathe?

Ever since this morning it hurt in the middle of my right side to breathe. It seems to only hurt when I breathe. I'm pretty sure it's not appendicitis because I checked the symptoms and I think the only one I have is it hurts the right side to breathe. Yesterday it hurt to pee, but now its fine, and now I'm having pain on my right side. Does anyone know what could be wrong with me?