Tonight while I was in the coop, I noticed one of my hens having "neck tremors". After she eats her food, her head goes up and her tail goes down and it looks like she is shaking her neck back and forth to get the food down. Our flock recently had canker, and it looks to me like she has a little (I will have to treat that). Is it the canker that is making her do this or something else? Thank you.