Hey! This is what happened to my tongue over the past few weeks and I get the moucous thing a lot. It's just started to heal and the white coating is going.
I was advised by a Chinese Herbalist to stop eating oily and spicy foods because I have a heated gut! That's what I've done and it's working. I think most people would be ok but I have a really weak immune system. I hope your friend shows signs of getter better soon.