I have a year old chicken that has been sneezing and sounding congested for a couple of months now. It hasn't gotten any worse, and she hasn't shown any signs of distress, so I decided to let run its course ( I don't use antibiotics unless necessary). Yesterday I noticed that she was walking a little strange, side stepping all of my other chickens oddly, like she couldn't see them well. This morning I caught her, and I noticed an awful smell. Under her eyes and toward her beak is swollen, and she has colored discharge coming from her nose. She doesn't wheeze, she's eating and drinking normally, and her eyes are clear. I thought it might be Coryza, but she hasn't infected any of my other birds, and she's had it for months. Any ideas on what she has, or what I should do?