Hi,
Welcome to the ehealthforum and I am really glad to help you out. In view of the symptoms described you, there are 3 possiblities which come to my mind. Firstly, a cardiac problem needs to be ruled out.
For the same, only a physical examination is not sufficient and he will need to undergo tests like stress EKG, Echocardiography, CT angiography to rule out a coronary artery disease problem.
Secondly, an upper GI endoscopy to rule out esophagitis and esophageal manometry to rule out a spasm of the esophagus. I sincerely hope this helps. Take care.