I have hen that we just noticed is having a hard time walking and standing. When she walks she is very unsteady and though she can run its not normal and still wobbly. She has laid so she's not egg bound, her crop is not full, and she eats and drinks. We noticed a few days ago she wasn't as active as the other hens. I have separated her in her own pen and she just sits there. What's wrong? What do I need to do for her? I also think she is molting...or someone is plucking her feathers pretty good. Oh and no mites or lice.