Fowl Pox? Bronchitis? Please Help

This started about two days ago. My rooster came in with what sounded like a "stuffy nose" and acting like he did not feel well: tail hanging and head down. He has not crowed or made any normal noises. Since I've brought him inside (away from the other chickens), he has only gotten worse. I started out by giving him vitamins to try and assess his symptoms. He now keeps his mouth open constantly and seems to be gasping for air. He has "sneezing attacks" that sound like a baby sneeze (high pitched). There are white "ucler-like" spots inside his mouth. And, he has horrible horrible breath too! His comb is turning purple/black on the edges.
There is NO discharge from his eyes nor nostrils, but still sounds "stuffed up".
He is my pet, such a sweetheart! I'm very worried and do not have a vet that treats chickens where I live that I can find (called every vet I could get a number to)....

 

I do have him on some antibiotics as of yesterday. But, I don't want to be treating for the wrong thing. I was really hoping to just get some insight on what might be wrong with him. Thank you, all the same