If the vet is saying, "oh it could be this, this, or this," and then is sending you home, go see another vet! She should be testing for these things! Sneezing and crusty eyes are signs of a possible URI (upper
respiratory infection).
I searched for a disease called "Temperance" and found nothing. Perhaps you should ask the vet if the disease has any other names.
His symptoms don't match the ones for
canine distemper at the moment.
Ultimately, I think you should see another vet. One that will test for all possible types of illness, target one, and quickly put your dog on an antibiotic to cure it.
Good luck! (And keep us posted!)
Note--
It's a shame you're not in the deeper part of Louisiana (where I'm from). I could have recommended you to a WONDERFUL vet!