It is starting to sound more like coryza because of the odor. You will need to flush her eye out with saline and clean it with QTips. Then I would get some Terramycin eye ointment, Vetropolycin ointment, or some Vetericyn eye gel from a feed store, and apply it twice a day after cleaning any gunk out. Or you could sacrifice the sick hen, and refrigerate her body to ship or take it to your state poultry vet for a necropsy. That is a good way to find out what disease that is affecting the flock. These chronic contagious diseases are spread by a carrier, either a chicken or by the germs getting brought into the flock. Coryza affects only chickens, but it may be carried in by other birds. I would treat for MG if that is what it is, but for coryza, I would cull any affected hens. Either way, the flock should be closed to new birds, and keep these birds until they are all gone. Most respiratory diseases will only remain on equipment and around the coop for several days once all birds are gone.