Hello, I can understand your concern for the spreading rash in your daughter. After analyzing the query I can get that your daughter probably have mild atopic dermatitis over the legs. You have not mentioned the exact diagnosis given by your doctor. I suggest you to take a second opinion for the rash as there could be multiple possibility of rash. In my patients with your kind of condition I generally suggest to do cold compression over the affected area. I also prescribe an antihistamine to reduce the intensity of burning and itching. You can take further guidance from a dermatologist. All the best.