Can you describe any other symptoms--watery eyes, eye bubbles, runny nose, swollen eye or face, rattles or wheezes? Chickens can sneeze because of dust, molds, ammonia fumes from droppings, and respiratory diseases. Here is a list of common diseases--look at infectious bronchitis, mycoplasma gallisepticum, infectious coryza, and ILT: http://edis.ifas.ufl.edu/ps044