What if you are itching and have some bumps on you that started on your arm first and then your back. what could it be?

Poison ivy /oak: poision ivy/oak Poison ivy treatments are usually limited to self-care methods like calamine lotion , and the rash typically goes away on its own within two or three weeks. If the rash is widespread or results in a large number of blisters, your doctor may prescribe an oral corticosteroid, such as prednisone, for poison ivy treatment. If a bacterial infection has developed then antibiotics.