I think I finally realized what has been the cause of my burning mouth: Flonase. I avoided it for other reasons but just started it up a few days ago to clear my sinuses. And sure enough burning mouth and tongue returned! Ugh!
OMG! Finally, a kindred spirit! One of my first FMS symptoms was this feeling on my tongue that I'd eaten really hot HOT sauce when I hadn't. My tongue would burn as if everything I ate had chile in it, especially fizzy drinks like Coca-Cola. I never did get a doctor who could tell me that it was all part of FMS. I have decided that it is. It does get worse when I'm in a flare-up. It also clears up for a bit when I have had to take a course of Diflucan for yeast infections that I seem to get alot since being stricken with FMS in 2000 so perhaps it is related to yeast overgrowth. I dunno. I do have many sensitivities to virtually everything, so it is a hit/miss kind of thing with regard to treatment. I have many allergies and am on Allegra, Flonase, and Singulair. I try to keep my sugar intake to a minimum but when I'm in a flare-up, sugary things seem to be what my body craves, especially when I'm in "fibro-fog".
Yes, I've had this off and on most of my life. Sometimes it drives me nuts. I thought it might be my allergies. Maybe it's the allergies and the fibro.