Have you been to a country fair or did you bring in new birds lately?
As ILT (Infectious Larygotracheitis) is highly contageous you would see more of your hens showing the same symptoms very soon.
Infectious Laryngotracheitis in Poultry - Poultry - MSD Veterinary Manual https://www.msdvetmanual.com/poultr...eitis/infectious-laryngotracheitis-in-poultry
As ILT (Infectious Larygotracheitis) is highly contageous you would see more of your hens showing the same symptoms very soon.
Infectious Laryngotracheitis in Poultry - Poultry - MSD Veterinary Manual https://www.msdvetmanual.com/poultr...eitis/infectious-laryngotracheitis-in-poultry