I added 4 new chickens about 3 weeks ago and all are doing well except for the light Brahma. She is 2-3 years old was fine when I got her but starting acting sick about a week ago. She lays on the ground and will not get in the nest or hardly move. She walks like she is drunk, stumbling around and her head keeps bending back in crazy ways. I added proantibotics and electrolytes to her water and even gave her some by syringe. Seems to only be getting worse... any Idea ? She was literally fine and normal the first few weeks and all the other hens are fine.