What Causes Sharp Shooting Back Pain?

back pain, upper left, sharp pain seems to project through back to front chest rash (like rickets or shingles),numbness of flesh left side of chest and back starting from the left shoulder blade extending to the left breast...about five inches wide. Same area as rash (above).No problem breathing, chest is clear, no coughing Blood pressure has always been normal but over the last couple years, some times minor elevations with stress.Male 73 years Caucasian 210 lbs, six feet (never gets sick...like never)History:minor back problems but usually treated by Chiropractor Smoked for many years but quit about 16 months ago.