Okay---so you have determined that what your bird is doing is not normal. Especially if you haven't found a vet who understands the concept of chickens with names, or if you don't have the money, time or means to get to a vet, check through these links.
Build a list of symptoms, then get an idea of what it could be
Handbook on Poultry Diseases
LOADED with info...pretty technical, but WOW!!!
Summary of Avian Diseases: Fungal, Nutritional, Tumors, Parasites & Miscellaneous
Pretty heavy going, and a big page....but good info!
Respiratory Infections In Domestic Poultry Flocks
A NebGuide worth your time and attention!
Rational Empirical Antimicrobal Therapy in Small Animals
A good philosophical overview with techinical pointers and information.
7M Farm & Herbal
natural, herbal and chemical free products for animals and livestock