Disclaimer: I am not a medical doctor
. I have had symptoms like those you describe for over twenty years. Due to his age and the fact that he has been seen by doctors a "few times" you might consider this to be anxiety
or stomach related. Either will give you symptoms of chest pain
. For stomach problems you might try over the counter drugs like Prilosec
O.T.C. or Pepsid. For anxiety try some relaxation, vacation, exercise, etc. Stay away from coffee, pizza, spaghetti, etc.
Most important: see a doctor!