What Causes Pain Under The Ribcage To The Back?

hi there i have pain under my left rig cage & all the way through to my back. had it for about 4 days & now have a rash. the rash is from the front to the back & is red & slightly itchy. it hurts to breath in & i am having sharp stabbing pains under the rib. i have read so many things i'm starting to worry...