I would call another vet and get them in asap.
It is highly contagious, and they can develop conjunctivitus and pnemonia as well.

We've just gone through this. Sherman developed KC, and the vet told me that some honey on bread would help stop the cough. I also tried a child's cough supressent, which is supposed to help. Actually I think Sherman gaged on that more than his cough gaged him.

The vet said it's usually a combination of viral & bacterial infections, and they may give a couple things to treat it. Sherman was on an antibiotic & a cough medication. It's been a week, and he's almost over it. His eyes cleared up right away. He's still hacking a bit.