Diagnoses for sick chicken
I found a rooster in my pen today that is mostly grown an he has clear drainage from nose an mucas in mouth an one side of his head the whole way around his eye an same side of head is swollen to the point of his eye swollen shut can you tell me what this sounds like an how to treat him an possibly how to treat my whole flock baby chicks an adult birds please an do i need to get rid of my whole flock?
Diagnosis of poultry diseases is typically done through a necropsy since many diseases have the same clinical signs. Do you have a diagnostic lab near you? I can't tell since no location is indicated on the question.
Mixing of young and old birds in the same flock is typically not recommended since the older birds could give the younger birds diseases that the older birds were previously exposed to and are now carriers.
Sounds like a respiratory disease which is usually viral and there are no antivirals approved for poultry. Without knowing what country you are in, and I can't say what medications you can legally give. An antibiotic (broad spectrum) make help prevent any secondary infections but will not cure the rooster.