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Your normal EKG,Blood reports and Normal Treadmill test effectively rules out underlying cardiac disease.(Although treadmill test is 85%sensitive at most in ruling out angina but your age and well controlled BP and Cholesterol
are reassuring with history that does not sound typical of angina.)
Your symptoms do sound like GERD(Gastro-esophageal reflux disease)which is due to reflux of acidic stomach contents into throat causing pain and throat irritation
and at times bad taste in mouth.
You may need to have strong anti-acid drugs like PPIs(Proton pump
)which reduce acidity by >90% and effectively control the symptoms.
If still not relived then drugs which increase gastric motility and close esophageal-stomach sphincter like Metoclopramide
can be tried.
I hope that following link will give you good information
These are some options which you can discuss with your physician.