I moved your thread into the correct forum.

Snakes don't "cough" and they don't usually get over a "cold" the same way a person would. It sounds like something serious is going on and it's not something that will get better by itself. You may have to travel some distance, or maybe you can find a herp vet willing to do a phone consultation. A phone consult is unlikely to be very helpful though, as you'd probably need someone to actually show you how to administer the medication. Where DO you live? You might be surprised to learn there are qualified vets within a reasonable distance...they're not all in big cities or anything.

What are the temperatures in the enclosure? What kind of enclosure is it? Humidity levels? Does it share a home with another snake?

How did you "treat" with vicks/eucalyptus?