I'm sorry that your question wasn't answered in a timely manner. We don't have many avian vets on this site. Here's what you need to know:
1) Respiratory infectious agents can be bacteria, viruses, or fungi yet symptoms can appear to be the same to poultry owners and vets alike.
2) Respiratory infectious agents can also cause diarrhea and reduced egg production. Infectious bronchitis (coronavirus) is a good example of such an infectious agent.
3) Scratching at their eyes indicates ocular (conjunctival, usually) involvement in the infection. The nasal discharge suggests sinus and nose involvement.
4) An avian vet (please see here: www.aav.org) would be needed to clarify which infectious agent(s) you're dealing with. Cultures, virus isolation, and PCR (DNA-based) testing is performed. Necropsy of a newly dead bird that was refrigerated (not frozen) is a valuable diagnostic particularly when large numbers of birds have been exposed to the infectious agent as I expect is the case here. A vet can help arrange a necropsy for you.
5) If you don't have such an vet available to you, you might presumptively treat with the antibiotic tylosin (Tylan-50 in your local feedstore) dosed at 20-30 mg/lb given intramuscularly into the breast muscle once daily for 5-7 days.
Please respond with further questions or concerns if you wish.