You could try searching up Wry Neck, my little Silkie has that right now and she's been doing okay, yet my hen Bravewing (yes, the one on which I named my account after) ended up dying from it. Your chicken sounds a little different though... Watch this video I found of someone's chicken and...
Hmm... First of all, I'm no expert. I'm just going off of what I've experienced, And after looking at the picture of your bird, I feel like I've seen this before. First of all, has she been twisting her neck around in a snake-like motion and backing into things? Second, does she walk around...