She acts like she has a bit of congestion but other than that acts and looks very healthy. That "chirping" sound gives a good indicator. And scratching could be due to bit of congestion in nostrils and she is trying to clear it.
If she were mine I would give her Tylan.
If you are worried about worms of any type give her Ivermectin. Either drops on back of neck or if you use horse paste wormer give her a dab in her mouth. Good luck!
I copied this out of a reference to poultry diseases..
Infectious Bronchitis
Synonyms: IB, bronchitis, cold
Species affected: Infectious bronchitis is a disease of chickens only. A similar disease occurs in bobwhite quail (quail bronchitis), but it is caused by a different virus.
Clinical signs: The severity of infectious bronchitis infection is influenced by the age and immune status of the flock, by environmental conditions, and by the presence of other diseases. Feed and water consumption declines. Affected chickens will be chirping, with a watery discharge from the eyes and nostrils, and labored breathing with some gasping in young chickens. Breathing noises are more noticeable at night while the birds rest. Egg production drops dramatically. Production will recover in 5 or 6 weeks, but at a lower rate. The infectious bronchitis virus infects many tissues of the body, including the reproductive tract (see
Table 1 ). Eggshells become rough and the egg white becomes watery. (See publication PS-24, Egg Quality, for other causes of poor egg quality.)
Transmission: Infectious bronchitis is a very contagious poultry disease. It is spread by air, feed bags, infected dead birds, infected houses, and rodents. The virus can be egg-transmitted, however, affected embryos usually will not hatch.
Treatment: There is no specific treatment for infectious bronchitis. Antibiotics for 3-5 days may aid in combating secondary bacterial infections. Raise the room temperature 5°F for brooding-age chickens until symptoms subside. Baby chicks can be encouraged to eat by using a warm, moist mash.
Prevention: Establish and enforce a biosecurity program. Vaccinations are available.