Did you just come off an antibiotic? A simple explanation for your symptoms could be a burning tongue form an oral yeast infection. A couple of months ago I took Levaquin (never ever again) for a sinus infection. Among a host of other side effects I got an oral yeast infection (thrush) I too felt like I had a coffee burn that never would go away. My doc gave me 5 days of Nystatin swish and swallow and my infection and burning tougue went away. And btw my thrush was not severe and my doc almost missed it, but the burning tongue clued her in. Note that for some it takes more than 5 days on the Nystatin.