Yesterday I found one of my girls sitting in the corner of the coop, rolling her head around backwards. She was sitting on the ground and looked like she was straining. I checked to see if she was bound but felt nothing in her vent and her abdomen felt normal. I checked her poops and they were also normal. Her comb is bright red too. I left her for the night to see if anything changed, and she was still acting that way in the morning. I came home from work and she is now standing and walking, but every once in awhile she'll fall completely backwards, flap her arms around and shake her head.. much like a human having a seizure. She has had a recent eye injury (something was stuck in it), and I kept her separate in a clean box with food and water while I treated it. She gets vitamins, and I also had to give flock antibiotics recently. I put apple cider vinegar in their water and they also get plenty of oyster shell stuff. Any ideas?? She seems to be a bit better, but I'm pretty worried that I'm missing something big. The other girls are fine. They've shown absolutely no signs of any health issues. We've also had some recent rainy weather and hail. Any ideas?