Not sure which reply chain to jump into here, but during endoscopic evaluation have you ever had biopsies taken to check eosinophil counts in your stomach or esophageal tissue?
I've had several gastroscopies and always had biopsies taken. Eosinophils were within the normal range, so whatever I have is not a true allergy.
More than an allergy I was curious about something to the effect of eosinophilic esophagitis or one of the other eosinophilic gastrointestinal disorders. I present with a similar timeline and symptoms to your description and was querying to see if that was a point of divergence.