A few days ago we noticed our one chicken was holding her one eye closed occasionally. The eye appears to have a cloudy film or discharge in the corner. We have been treating with VetRx and vetericyn eye gel for two days with not much improvement, I am about to start terramycin eye gel. However, I have since noticed that several of our chickens seem to be shaking their heads quite frequently when they're sitting in the coop and am worried that this may be a respiratory infection issue instead of just an eye irritation/infection of the one chicken. So far there hasn't been any other symptoms though. Should I jump to treating all with an antiobiotic and which?