Could they be molting? When they molt their feathers fall out, sometimes in weird places all at once. One of my hens will molt from the head down. She goes bald then the rest follows. Being disheveled can also indicate a health problem. Could they have worms, or mites, or lice? Check them over carefully for bugs. Maybe do a collective poo sample and ask a vet to run a fecal.
When chickens don't look quite right you want to take notice and do some investigating. Chickens are very good at hiding illnesses, due to the fact that they are prey animals. You don't want to show weakness when you could end up as someone's meal.
Until you can get a poo sample into a vet, try supplementing their food. This is helpful for molt or for illness. Give them some mashed hard boiled egg, hulled sunflower seeds, mealworms, even cat food is good (not too much on the cat food as it has too much salt for chickens). Vitamins can help, like Avia Charge 2000 (order from Strombergs online) or Polyvisol baby vitamins (without iron) which you can buy from most drug stores.
Hope this helps.
