I would get some oxytetracycline or Tylan from your feed store and treat her for a possible respiratory disease. Tylan comes in a powder for the water, or you can get Tylan 50 injectable, and give it orally or by injection. Dosage of Tylan 50 is 1 ml twice a day for 3-5 days for a full sized chicken. The others have already been exposed, so they may or may not get it. Here is a link to read about the respiratory diseases infectious bronchitis, mycoplasma (MG,) coryza, and ILT: http://edis.ifas.ufl.edu/ps044
It is not going to hurt her to give antibiotics. I don't recommend them unless there is a reason to use them. Wheezing is not normal. Sneezing can be a virus that will not respond to antibiotics,m but could also be a bacterial or mycoplasmal illness. With any antibiotic, I would probably throw out any eggs for at least 3 weeks.
- Monkey Lookout