What Causes Itchy Rashes, Blistering And Boils?

Have itchy rash on back forearms some blistering, armpit boils, metalic taste in mouth, sometimes severe itching on right foot instep
Antibiotics for 20 days seemed to reduce symptoms, antibiotic cream reduces boils, gold bond extra strength lotion reduces itching.
Trying gluten free products as daughter just diagnosed with celiac & possibly lupus