Dear Tom,
Is it an Autoimmune disease? I don't know that name either but I do know of Sjögren's syndrome and in PubMed, the two words come up together a lot. (Gougerot and Sjögren's). I wonder if it's the same or a combination of symptoms? A dear friend from the TS forums and chats from years ago had Sjögren's syndrome. I haven't heard from her in years but lots of what I've just read in your posts sounds familiar.

take care there,
Lara