Do you have photos?
How old are the hens?
Have you gotten any new chickens within the last 30 days?
From your description, you are dealing with a respiratory disease. Mycoplasma and Infectious Bronchitis are fairly common. If they have a foul odor about their head, then it could be Infectious Coryza.
Since there is respiratory distress, then you probably need to see if she will respond to antibiotics. You can find injectable Tylan50 at most feed stores. Dosage is .20ml per pound of weight given orally 3 times a day for 5 days. If you can only give it 2 times a day, bump up the dosage to .30ml per pound of weight.
Do keep in mind, as you are finding out, respiratory diseases are contagious. Even if birds recover, they remain carriers of the disease.
http://edis.ifas.ufl.edu/ps044
What are you goals with these chickens?