Poison Ivy, that IS a great resource! And I agree with you Cutestchickenfarmer, it does sound just like Botulism. She now seems to be almost paralized in the legs and doesn't seem to move her wings either, so I'm not sure about them? She can untwist her neck long enough to peck at food for a few seconds here and there, then the effort it takes seems to get to her and she slumps back into the twisted neck on the ground position. I'm going to call my chicken lady friend who seems to have all the answers (and finds good homes to my excess roosters too!). I'll keep you posted, but it doesn't look too good for the poor girl.....
Another thing, I'd think if it were contagious, the rest would have shown some signs by now? She's had this strange twisted neck, off and on, for several weeks or a month even? None of the others pick on her or anything either, and she seems comforted knowing they are nearby (she "bocks" back at them when they start squawking). I don't know...