One of my 5 backyard layers (likely 3-4 yrs old) is showing neurologic signs: she is moving forward but then starts going sideways. She also sits low on her legs, meaning she is not walking upright but her hocks are lowered down. She also has lost her feathers on her back since about a week or two. I thought she was just molting. She has never been sick, nor have the others. She looks skinny, but is eating normally it seems. They are on organic layer mix with lots of kitchen scraps. Anyone any ideas?