Burning in upper chest with vigorous aerobic exercise

I'm a 59 year old white male in very good to excellent physical condition, participating in vigorous step aerobics and group moderate weight training, one hour of either, 5 X week for the past 3 years; cycling at times (though not in the last few months) for 30 to 60 miles for the past 12 years; and doing step and other aerobics regularly for the past 20 years.

A month ago I began experiencing a raw burning in the upper chest (as in windpipe and bronchial area)ONLY when doing step or cycling vigorously. When I continued, I would get some tightness/pain under both armpits.

I back off for a couple of minutes, and it subsides. But, trying to keep it up until I

[anacyde]

Your symptoms could be anything from dry air to GERD to a heart condition.  I do get those symptoms and I have no clue what mine are, though the heart cause has been ruled out for me.  Your GP is being cautious.

Why the ACE and the other medication?  Are both for blood pressure control?