Sounds like you might need some louse powder! It is quite common for sick chickens to become infested because they are too poorly to dust bath and preen as they normally would. Many people seem to think these pests can be the cause of death because they see heavy infestations on very sick birds, but in my experience there is usually an underlying illness that allows them to flourish and it is the illness that is the actual cause but people usually don't get a necropsy to find out and just assume it is the parasites.After holding her for several minutes, I am itchy as heck.
Can you take some video footage of her and download it to You Tube or Vimeo and post a link to it, so we can see how she moves? I'm leaning towards possibly Marek's disease, but seeing her would give more idea.