Mouth ulcers? Warts? Thrush? What are these?

[Ludi-doodi]

Norman, a semi-retired 23yo cushings suffer has had these appear in this mouth (first spotted on Thursday). Any idea what they are or what causes them? The vet will be called, but just wondered if anyone knew what they were. He also has one on each side of the underneath of tongue almost directly above where these are.
Whoops images are bit big and not great quality, but it was difficult to get him to stand still whilst hanging on this lips and taking a photo!

 

[Box_Of_Frogs]

They look like very bad mouth ulcers. I'm wondering if they are linked to a failing immune system. Has he been on a course of broad spectrum antibiotics? Poor lad - they must be sore. Is he losing weight? Hope vet can shed some light on it x