My mother is 77 years old and for almost 15 years has white thin lines that form under the skin that look like scars. They burn and get much worse in the sun and heat. The lines look jagged and some cross over others. They are primarily on the front and back of her arms and occasionally on her face and legs. The skin is not broken. One dermatologist started burning them off and another said it was yeast. Any ideas? She has been tested for Lupus and it was negative. When they get worse she becomes very tired.