My Sister Is 63. The Skin On Her Arm Itches

My sister is 63. The skin on her arm itches and burns if it gets the least amount of heat from wearing a long sleeve shirt. A doctor said it was from too much sun in her life time. Shr uses ice packs to relieve but she can't ice it 24/7. What can be done to help her as it is now spreading to her other arm. It is debilitating for her. Is it an allergy?