How To Treat Extreme Pain In The Left Arm ?

My husband had anxietiy last night in his chest. After several hours of resting it did go away...rough week with a broken down vehicle, monies, etc. Tonight he is complaining that his left harm has been hurting for over an hour starting up at the left shoulder. No chest pain, and no muscle pain in the Arm just extreme pain going through the arm that he doesn't want to disturb it. He is over weight in his stomach area by 50 lbs or so, but not sure if this is a weight issue or a stress issue.