Many times just one eye is involved in a respiratory infection. Head shaking can be another symptom. If the swelling in the eye is due to infection, I would probably treat her with Some Tylan Soluble Powder, Erythromin (Gallimycin), or oxytetracycline in the water. Tylan50 injectable can also be used as a shot. Read this link about diseases, and look at mycoplasma gallisepticum, infectious bronchitis, and coryza--see if it fits: http://edis.ifas.ufl.edu/ps044