What Do Pain And Discomfort Behind The Breasts Indicate?

8 months ago i noticed a very pinpoint pain(discomfort) in my left chest behind my breast, and it has continued to today, with fluctuations in severity. I have had chest xray, ct scan, ekg, echocardiogram. All normal except for a small spot in my lung on the chest xray that did NOT show up on the following ct scan. Blood work shows low electrolytes, low nonfasting blood sugar, low progesterone, low zink and calcium. I have had many episodes where I thought i was having a heart attack(pain down my arm, neck and back), but with diet changes, especially not eating late at night I have stopped those. my naturopath has pretty much narrowed my symptoms down to some type of esophageal injury. The past 2 days I have been on pantoprozole and my symptoms seem less, but not gone. I have no plans on taking it forever, just a few days as a diagnostic tool to see if it gets rid of my symptoms, and then use natural treatments. Do you think it could be something more sinister than an esophageal injury, and do you think i should have an endoscopy? Thank you, Shannon