i had a chicken that was doing the same thing, or at least something similar... i'm wondering if the chicken had a blind eye or something though that caused the unbalance. It would attempt to walk, but to make any advance in movement it had to keep a wind out for stability... after a step or two it would just tip over then flail on the ground. I tried some general anti-bacterial medication (can't remember the name ATM) that you mix in their water for a 10 day duration hoping that would clear things up, but no luck...
