Answer

Recommended vaccinations for small flocks include:
Marek’s Disease; Newcastle Disease; Infectious Bronchitis; Laryngotracheitis; Fowl Pox; Fowl Cholera and Avian encephalomyelitis.

With the exception of Marek’s Disease vaccination, all other vaccinations should be given to stock over 10 days old.
There are many more details including explanations of the diseases and where to get the vaccines here: http://edis.ifas.ufl.edu/ps030   

Get in touch with your supplier for availability of vaccines. For small flocks it’s a good idea to find another small flock owner in your area and discuss sharing the cost of vaccines since they tend to come in large flock vials.

Call your local 4-H club, cooperative extension, farm supply stores, Humane Society, ASPCA and sometimes your local animal control agency will have resources for you.

Any other farms, big or small, may also be helpful.

The diagnosis must be made with a hands on visit to a qualified vet, but I suspect Newcastle's.   

There are three forms: Lentogenic (mildly pathogenic), Mesogenic (moderate) and highly pathogenic (Velogenic).

Newcastle's is often a sudden onset disease with symptoms which may include: watery discharge from nares, labored or open beaked breathing, facial swelling, paralysis, trembling, and twisting of the neck (involvement of the central nervous system).

Mortality can vary widely from 10 to 80 percent depending on the pathogenicity.

Again, this is just one possibility based on your indications.   You really need to confirm this with an exam.

Good luck and by the way, good instincts in separating them.