HELP!! Rapidly spreading respiratory problems...Could it be Avian flu?

[ChickenCharmer]

This morning I opened the coup and Henrietta the EE seemed to be breathing strangely. Each breath sounded something like a hum. So I separated her.
A few hours later I checked on her and the humming seemed to have stopped, but she was still breathing strangely. Then I heard more humming, wheezing, coughing and sneezing coming from Jade the Minorca hen, and it sounded much worse than Henrietta's, so I separated her too. After I did that, Remus the OEGB rooster started to wheeze, so he got separated as well.
I noticed nothing like this in the morning, and now about three hours later, Jade and Remus joined Henrietta. Could it be Avian Influenza? Should I be worried about my flock? Will my chickens die?

Please help me here.

Thanks

 

[Sonoran Silkies]

Much more likely to be one of several respratory diseases than AI. Other than the breathing sounds, what symptoms are you seeing?