Well, two weeks on gluten free is not nearly long enough.

Usually people see some improvement if it is going to happen at 3-6mos.

Many neuropathies can respond to supplements. So since you have no visible pathology with all those scopes, etc...you have to think on a cellular level.

Your symptoms have changed character. I think this is due to all the mechanical irritation you endured. We've had posters here and at our old site who posted throat problems after intubation during surgeries, for example.

Ganglionopathies at the dorsal root ganglia. This is a graph showing the distribution of a sensory issue:
http://neuromuscular.wustl.edu/antibody/sneuron.html
This list given is also helpful... of the various things that need to be ruled out.

These may respond to lidoderm patches, which were originally made for Zoster neuropathy which occurs in those ganglia along the spine. You could try asking for them, and place at various locations along your upper back and neck along the spine, in order to find the right location. Follow directions carefully when using these if you get them on RX. When shingles activates, it follows nerve pathways and often appears along a specific area. I have mine down my right arm. Hubby has his along his chest area and back. In spring and fall for some reason Zoster seems to activate and we both get pain sometimes, still. Your herniation in the back may be another thing separate from your original problem.

Try the supplements and see it they help. Krill oil has no aftertaste at all, the caps are much smaller, and is just like fish oil. The red color is a useful antioxidant. I use MegaRed.

Autoimmune and viral triggers may be your culprit. But you didn't have any of the burning did you before you had all those tests? This new symptom came after?

There are CNS problems that affect the neck. Most of them are dunning and frightening. Since you don't seem to have the dysphonia, or difficulty swallowing anymore, I don't think you have a major issue. You can always look at that later in time if you choose.