Please register and tell us where you are located.
Your birds are displaying the classic symptoms of respiratory infection.
PLEASE isolate the sick birds put them in a warm, stress free- and draft free environment, make sure to feed them if they are not eating and they will need medication asap, such as Aureomycin concentrate and tylan, or Doxy T, or Ornicure. You don't want to wait as secondary infections can quickly manifest with this disease, as well this is a serious disease that requires immediate action.
Make sure to keep you coop clean and dust free, and that there are no air drafts on your birds.