Exercise & Injury what to do?

Tebbspcad

I've been activly exercising for a few weeks now & have managed to pull a muscle in my back/rib cage this morning, god only knows how i've managed that! (I was doing Jillian Michaels' 30 Day Shred, workout number 2). Am i alright to still exercise as I'm keen not to sit around but breathing hurts like hell at the moment. Any advice would be much appreciated .Thanks