My 81 year old mother has had a skin rash (arms, upper legs, breast, abdomen for almost 9 months. Has seen primary care an dermatologist who have prescribed OTC cream and several (expensive) creams, Has not helped and now she has developed blisters (bubbles) on her arms. Use clear laundry detergent and have tried antihistamines, vacuumed her apartment including furniture and mattress. What now?