True chicken allergy
is quite rare, and blisters with pus is not a typical allergic reaction
unless she has scratched the itchy areas so much that a secondary bacterial infection has occured.
Flucloxacilin taken three times daily is the treatment for skin abscess
and you can also apply mupirocin
cream that will help.
Do check with your doctor about the dosage as it is best to decide on the weight of the patient.
Hope that was useful.