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I also have a "geographic tongue", or so said a Dr. years ago.  I went into
him for my bowel distress (which he called Irritable Bowel Syndrome--HA!).  I
told the Dr. that my tongue would burn and swell when I ate certain foods.
 He said there was nothing that could be done.
 
Now on a GF diet, I have quite a nice looking tongue (as tongues go) and no
pain.
 
Go figure.
 
Lorraine