32 male, complain of chest pain at 2.00 a.m. Hospitalised. ECG normal. B.P. normal. Pain killer and sedative?

Pain killer and sedative given. Relief in 5 minutes. Sound sleep. Morning OK. No weakness. All tests in the morning normal. At night he climbed two floor starrs while pain. No proble. No sweating, no breathlessness. Moreover, 2 months ago his treadmill test was absolutely normal. His endoscopy, biopsy, sonography all for UGI normal. But surprisingly, he has chest pain, gas and bloating almost every 2 month. Acidity not much. Indugestion, no. But has a habit of chewing tobacco and eats fast with minimum chewing. Mostly vagetarian and otherwise athletic in health. Runs and walks almost regularly. Very fit. Weight 75 KG., Height 5' 6 1/2". Gujarati Hindu, Indian boy. We wonder what exactly is the cause of this periodical chest pain. Doctor treating is very good and expert. M.D. But yet we are puzzled. Please try to answer ASAP.