For several years now, when I eat dark chocolate, it taste sweet & delicious until after I swallow and then I get a very unpleasant, bitter taste in my mouth. For several months now, I wake up with my tongue seemingly glued to the roof of my mouth feeling very dry. This goes for my lips also. I think it may be a spreading of my SFN as my tongue will remain sore throughout the day. I'm worried but awaiting a referral to a new neurologist.