What Causes Itchy Rashes On Arms, Shoulders And Back After Efudex Treatment?

One year ago I underwent efudex treatment on my lower legs. I have had serious lesions all over my legs, that I am told is an autoimmune reaction to the efudex and nothing helps. Have tried 6 different topical corticosteroids. Recently I was given oral prednisone 20 MG , for five days, then reduced amounts for a month. I was so happy that it helped to reduce and clear up the lesions. However they returned with a vengeance as soon as I stopped the prednisone. Also I now have itchy rash on my arms and shoulders and back. I am discouraged and cannot find a way to control the itching. Any other treatment available? 9