Coco is an EE hen around 8 months old. I only noticed this behavior today, but I have not been home for quite some time so I am unsure as to how long this has been going on. She does eat feathers and we've applied Rooster Booster Pick-No-More cover-up lotion to the other birds, but I've seen their disgusted "yuck!" head shake after pecking the lotion and this is most certainly not it. Here is a video that captures the unmistakeable spasms. We have the opportunity to take her to a vet tomorrow and thus I will update this thread with any new information, but if anyone has seen this before in chickens, please let me know your thoughts.