Could this be Marek's disease ?
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Where did you give the shot--in the breast muscle, in the leg, or under the skin in the back of the neck? I would keep her quarantined away from any other poultry you have in case she has a chronic respiratory disease, or something else. A minimum of 30 days is good for quarantine. Since she is ill, she may need some extra warmth such as a heat lamp, or brought inside. Mareks presents with many different symptoms, and can be confused with vitamin deficiency, weakness from dehydration or coccidiosis, and other problems, such as moldy feed, lead poisoning, and botulism. I doubt if the Baytril overdose caused a problem itself unless it was injected into the leg causing nerve inflammation. I would make sure that she is taking her normal feed, water with some SaveAChick or Rooster Booster vitamins and electrolytes. Add a little chopped egg and a tiny bit of plain yogurt. Hopefully this is just a temporary illness. Here is some read about Mareks and common respiratory diseases: