I have had same GI issues as you do for last four years. I watch my diet and get better but then I start eating pastry and bacon(sometimes) and coffee, and pain returns. But, now, pain does not go away even with diet. I am on strict diet like your. Have been to different GIs and surgeons and lots of test. I have pain right in the middle where two ribs meet. Had nausea for few months but now I am fine. I still have pain after eating. I am having a test done called Endoflip. They use a catheter with a small balloon to look at my esophagus and also to check LES, Lower Esophageal Sphincter to see if opens and closes when food goes down in esophagus.
Rarely, food gets stuck in my esophagus. I have a small hiatal hernia as well. I think going on a strict diet and staying on that diet forever helps me sometimes. I am also having a 24 hour probe done. They place a probe with camera through nose inside esophagus for one day to see if I have acid or non acid reflux.