I am male over 65 and had triple bypass 15 yrs ago. I started getting severe chest and back pain (from my waist to just under my arm pits both front and back. Sharpest pain is on left side below my rib cage. Have completed heart stress test and hear looks good. What is possible cause of this pain? It seem to get much worse about 1 to 1 1/2 hrs after I eat. Pain severe enough to require pain medication.