Been treating this hen on and off for over a month now with no real results. Her only real symptoms are frequent gawping, occasional sneezing, and her crop never seems completely empty. Although she is the largest breed hen we own - the only Dark Brahma in a sea of Australorps and Barred Rocks - she's always been low on the totem pole, so naturally hangs back, doesn't fight for food, etc. I honestly can't say if she's ever laid an egg even though she's just over a year old, but I do know the 2 weeks I kept her in isolation, she did not. I listened to her body, and there are no odd noises either from lungs or crop. She doesn't seem to have any drainage from nostrils or eyes, nor is her face puffy. I've massaged her crop, it feels just like any other: loose enough to do its job, obviously containing some grit and corn. I went ahead and tried hanging her upside down, just to see if anything would drain out, but nothing did. Her breath isn't sour, but very much like wild onion/garlic. I don't remember it smelling this way until she was in isolation. She also does not appear egg bound, or appear to be in distress in any way. She seems a little slower, disinterested maybe, sometimes losing balance but not often - like she just wasn't paying attention, not like neurological. Her vision seems fine, though, to pick corn out of a mix of feed and mixed scratch in my hand. In isolation, she barely drank or ate, even though she was given hard boiled egg and meal worms, yet her crop never emptied that I saw. She barely pooped, and the first few were tiny, grass green. Our chickens have 24 hour access to feed and water, daylight access to free range (their preferred feed), and a little over a cup of scratch/corn between 13 hens, once or twice a day. I admit, I haven't medicated her yet, except for some Vicks to see if she was congested, simply because I didn't know what to try and hate using drugs when I don't have to.