A man of 30yrs comes with sudden onset of severe constricting pain in the back between scapulae later radiating to the central chest. How to manage?

This is an emergency. Any pain which has a constricting quality in the chest and/or back area must be evaluated urgently. This description, presuming no trauma was involved, could be a heart attack, a dissecting aneurysm of the aorta in the chest, a severe constriction of the esophagus (swallowing tube), etc. All of these make this imperative that an immediate evaluation be made in the emergency room.
Could be serious. Severe chest pain (CP) warrants evaluation at any age. The probable causes of chest pain vary greatly by age, gender, family history, and other risk factors. Some causes to consider in a 30 year old include: pneumonia, pneumothorax (collapsed lung), pericarditis, aortic aneurysm (marfans), and esophagitis.
Emergency Room. Severe pain to the back and chest needs to be immediately evaluated by the er. This is a call 9-1-1 situation. Although some non-serious issues could be occurring (reflux esophagitis, etc.) severe pain always warrants an er visit.