What Causes Severe Pain In Upper Abdomen And Chest Area?

My son has, for years, hurt everyday in his upper chest - GI sometimes in the center of his chest . His doctor has treated him with stress medicine also muscle relaxers and indigestion medications, many different kinds, nothing helps. He has had every test from X-rays, stress tests, ekg (heart has always checked out good, he's had upper GI test and probably more I can't recall ,these over a period of at least 5 years & probably longer. Today he was walking on his job and had a severe pain in his upper abdomen/chest and his doc told him to go on to the hospital. That is where he is right now. Can you help? No other doc has yet. All his test he has had have all been good. Thank you.