Yeast irritate the surface of the mouth and it will be ed and bleeds. Of course with EDS we bleed easily, I would see if your doctor would be agreeable to a culture and the Niastain mouthwash. That way as you will know for sure. Usually, thrush looks like a cottage cheese like film. It is creamy. If it looks like fur it may be something else. Like dry mouth or even certain medications. However, your doctor should be able to tell you what it is, and not say I don’t know. maybe try another doctor? The scope and Bx being negative are good. So if it thrush it has not spread, but it almost sounds like something else.