So, I'm a chicken first timer. Picked up all my pullets from a local breeder that one of my friends has had good luck with. About a week in, one seemed a bit more lethargic than the others, but still generally ok. About two weeks ago I the same chick is unable to get into the coop. I immediately pulled it from the others and started treatment with some advice from the local feed store, and from what I could find online. The day after I brought it inside it got much worse, and it's condition hasn't really changed since then, about two weeks ago. I immediately started nutri drench, and duramycin added to water. After a week with no change, I stopped the antibiotic and just add nutri drench into it's moistened food, as it struggles to drink. About the only time it's head is up is when it's eating. Balance is off, and it seems to not be in full control of where it goes, choosing most of the time to back up, even after hitting a wall. The head is between it's legs circling most of the time... like in the video. The rest of the flock seems fine. Any idea what this is, or how I can treat?