white sore patch on tongue. please help.

Hello all.

I am posting this question on behalf of my mother because she cannot speak English.

A year ago she had a white patch which slowly progressed to the sides and middle of her tongue. In the morning when she woke up the patch was white, but later on in the day it would become red (more red than the rest of her tongue). She also felt soreness with these patches and a burning sensation when eating inappropriate foods and many cracks had formed on her tongue too. She went to many doctors and they weren't able to give a correct diagnosis. However, the patches and cracks cleared up after many months (nearly a year) and she became better.
Unfortunately the patch seems to be coming back and it's starting to effect the tip of her tongue again.
She is also menopausal. Could this have anything to do with hormones or stress?
Does anyone know what this strange disease is?  Any help would be much appreciated. Thank you.