What Causes Itchy Dark Spots And Bumps On Hands And Feet?

my sister is 28 years old. She has been covered in dark spots and bumps on her hands and feet for several weeks now. They itch and her skin is now peeling so bad that her hand is becoming raw and she can barely touch anything. She went to the doc who prescribed cream for it but it has only gotten worse. She has a son and he hasnt contracted it so it doesn't seem to be contagious. What could this be?