As healthy as he looks, it could be possible that something toxic affected
him severely. Birds have very sensitive respiratory systems and things
such as leaking gas, spray chemicals and various types of cookware,
some of the older non-stick can be very deadly in a short time. Remember how canaries were used in coal mines to protect workers
from mine gas. There are certainly many other things that can kill birds
quickly but he looked very good....although they are good a disguising
symptoms. A vet could possibly determine the cause of sudden but
not always. Sad that you lost your bud.