Mild Discomfort In Chest On Walking Fast, Feel Urge To Belch During The Episode, History Of Triple By Pass. What Could The Reason Be?

I had a triple bi-pass in 1994. Was a long distance runner and never smoked. Family on both sides had history of heart problems. Until recently, have had no problems or restrictions. About a year ago I noticed a little discomfort in the high chest area when I walk fast for a distance. [ I no longer run because of foot problems.] This discomfort is not always there, but when it happens I feel the need to belch. The belching seems to ease the discomfort. If I stop walking the tightness eases and the belching stops. But when this tightness happens it is always in conjunction with the belching. I brought this to my heart doctor s attention, and he didn t seemed concerned. As I said, this discomfort does not occur every time I have a fast walk. Eating and meals seems to have no baring because many of my walks are in the early morning, and have not eaten since the evening before. Thank you for any advice.