What Could Cause A Persistent Dry, Uncomfortable Spot On One Side Of My Throat For A Year?

Hi there, I have had what feels like a dry spot on the right side of my throat for almost a year. IT doesn t hurt, it s just very uncomfortable. I m constantly chewing gum to produce enough saliva to ease the discomfort. I ve had an MRI and have seen an ENT doctor and no one has an answer for me :-(