sick chickens

[Rangerschickens]

I need some help! My chickens have been sneezing like crazy I’ve done everything I can to treat for a respiratory infection & nothing. I’ve noticed some have droopy wings now. They’re acting completely fine except for the sneezing. Any idea what it could be? And treatment suggestions

 

[Wyorp Rock]

I need some help! My chickens have been sneezing like crazy I’ve done everything I can to treat for a respiratory infection & nothing. I’ve noticed some have droopy wings now. They’re acting completely fine except for the sneezing. Any idea what it could be? And treatment suggestions

How's the ventilation in your coop/housing?
Have you added new birds?

What treatment(s) have you tried??