Busted rib type pain in left side?hurts to breath

Strain, fracture ?: It is rare to fracture a rib without trauma, so you probably have a strain of the intercostal muscles, which are the muscles between the ribs. This can be very painful. The pain could also be referred from inside the chest, which tends to be more of a sharp pain. Rib strains can take weeks to resolve, but will improve with time. If it is not getting better you should have it evaluated.