New hen sneezing. What to do?

I have had two backyard hens for about a year, and recently decided to add two more. I currently have them in a quarantine pen. One of my detainees has been sneezing!! Not frequent or extreme, just maybe once every few minutes and a real slight "puff" kind of sneeze. She is also in a molt. I havent noticed any drainage from the nostrils or eyes. This has been going on since I got her, about 5 days ago.

I did some research and am really scared about CRD, even though her only symptom is sneezing.

I was stupid and put the new hens cage smack dab next to my own as recommended by the breeder (to make intros easier). Now I'm scared that the other bird in quarantine will have it (whatever it is), as well as my two old hens.

I have since moved their pens apart. How worried should I be? What should I expect, and what should I do? Is there any chance this could Be reated to our cold weather, or her molt and not be serious?

Any help or advice is greatly appreciated!
Thanks everyone