Hi CC....I'm sorry to say that it's yellow fungus disease. It's very contagious and hard to treat, often fatal. You can get some betadine from a drug store, dilute it with water to the color of iced tea. and soak him for 5-10 minutes [ warm water ] A vet can do a skin scraping to determine exactly, but that looks 100% like Y.F. There is an oral medication that is used , voriconazole. pretty much the only thing available.
Take him to ONLY a reptile experienced vet. If a vet gives you antibiotics instead of the voriconazole, the vet is not experienced with Y.F because antibiotics do not work on Y.F. If you do a Google search you can read up on Y.F.
Best wishes for your very sick beardie.