I understand your frustration in trying to find help...almost NO ONE here (Texas) will see a chicken or a goat (?), or even if they do, they have no idea what to do, or what they're talking about.  If there is any way to do testing, I would since you now have others w/ similar symptoms.  If he passes away, and you still are planning on having disease testing done, DON'T freeze him, but refrigerate him, if at all possible (maybe unheated garage where you are?  Sure you don't want a sick chicken in your home fridge, but anyway)  
Sorry, don't mean to sound like a Negative Nancy, but when I worked @ a vet clinic, we would have people who wanted disease testing done, but they had already frozen the pet, and freezing destroys the cells.  
Yes, keeping birds sure can be tough.  That's why I'm uber-weird about adding new stock.  
Good luck!!!