I mentioned trying that diet for Maui and the vet said no, it wouldn't
work.
He doesn't appear to have allergies. I am going to call tomorrow and ask
again. Maybe they can swab the ears and check under the scope again (for
the fourth time).

Going to Z/D wouldn't hurt one bit. If the vet isn't being proactive you
need to get a second opinion, even if you have to go to an emergency clinic
some night. It's pricey, but there's no waiting list. We've had good
compliance with clients using Z/D and great results. Once you see results,
(and it can take up to a month) it's pretty amazing and cheaper overall
since you are no longer seeing the vet for chronic problems, getting meds
and treating etc. What's to lose?

yes, we are leaving the first weekend in August!

We'll wave from Rodanthe. We leave next weekend!