It could be just a sinus infection or at worst Mycoplasma. Separate the chick from the others. I think the best thing would be to get some Terramycin eye ointment. If the eye has any discharge, wipe it gently with a clean cotton ball before putting ointment in the eye. Some tetracycline hydrochloride dispersible powder in the water at 1 tsp and a cup of cranberry juice per gallon as a fresh drinking solution each day should be given also. Vitamin c helps the absorption of "cycline" antibiotics and makes the water taste better. Do it for 5 days and see if there's improvement. If you see improvement in 3 days, continue treatment for 4 more days. Your local feed store should carry these products. Keep us posted on the chick's condition, and we'll go from there.
