burning, stinging tongue, what could it be?!

I don't know for certain what causes it... Perhaps eating acidic foods like chocolate or tomatoes or drinking red wine. But I have the same problem and I use regular table salt to get rid of the pain when it gets SO extreme. I apply as much salt as possible to the area of pain and let it sit on my tongue (trying not to get it wet from saliva). Let it burn and work its magic for as long as possible. Within minutes, it will begin to alleviate the pain. It does burn a little as it's working... But believe me, it's hardly as painful as the original pain... and it goes away as the salt dissolves.

Trial & error!