I have experienced something similar but I'm really not sure it relates to fibro. I would definitely ask your doctor. Please let us know what you find out.

Curious, did your tongue issue resolve?

Definitely see your doctor about this symptom, mostly to put your mind at ease and to help you with the pain. There could be many explanation from serious to simple causes. It must be terrible feeling. I attach a link to an article perhaps helps a bit to sort out your symptoms and figure out how to move forward with this. ENT doctor, dentist perhaps... Hope you feel better soon. I had burning mouth, tongue, throat pain for nearly a year without any explanation, drove me crazy, had seen my dentist... the pain slowly let up but flares back time to time for short periods.
https://mayfieldclinic.com/pe-glossopharyngeal.htm

Sounds serious enough to go to ER to me... Or at least contact your doctor asp... Please let us know what you find out? Hugs Dear