I tried a zillion different things, changing the food I ate, keeping my mouth well hydrated, using organic toothpaste (no Sodium Laurel Sulphates), non-
alcohol mouthwashes, baking soda mouthwash (yukky!) and so on. It all helped a little but didn't really ease the discomfort.
I became so desperate I finally went to my GP and stuck my tongue out her and she said "thrush!" and gave me a course of fluconazole which, touch wood, seems to be working.