Ok experts! I need some real help!

[Mother Clucker Free Range]

I have one chicken that is sneezing and one that seems to have the sniffles. My vet WILL NOT SEE CHICKENS..?? Wth?!
it’s pretty clear to me that this is some sort of respiratory infection. Is anyone an expert at treating these? Is treating this something a newbie chicken owner can do? If so can anyone direct me on what needs to be done?
Thank you

 

[Wyorp Rock]

Can you get some photos of the chickens?
A video of how they sound may be helpful - upload to youtube and provide a link.

How often is the sneezing? Is there any discharge/mucous from the nostrils, watery or bubbly eyes, facial swelling, coughing, rales, wheezing, etc.?
Do you notice if the sneezing come when they have been eating/drinking?
How old are they?
How are they housed?
What are you feeding?
Where are you located in the world?