...The other stuff, well, "I" would want to know. At this point, with all the medical care and vet visits, why not test for other stuff,
if nothing else, you can rule it out and stop worrying about it while you continue to treat his URI....
That's what I was thinking too...let the vet test for Nido, while you're there...and yes, a "break" for you & Yafe is long over-due.