nasal discharge, labored breathing, lethargic, not eating...??

[Nat123]

I have 4 hens now that are exhibiting the same symptoms. A stray chick from a neighbor's yard ended up in ours last week. I noticed it seemed to be sneezing, and probably spent at least 24 hours in our yard. I'm worried that it exposed our chickens to something, as first one hen was acting this way, now 4 seem to be suffering the same thing.
Labored, noisy breathing.. nasal discharge (thick at times)... lethargic all day... sneezing....
I found a link yesterday in one thread, to a list of respiratory infections, but not finding it today so far (forgot to save the link

)
Any thoughts, advice or suggestions?

 

[MommaOrp]

Maybe mycoplasma, ours have it at the moment, tylan or baytril usually fix this, catch it now before you lose them to it!