My Mom, 65 Years Old, Is Suffering From Tiny Dark

My mom, 65 years old, is suffering from tiny dark pimples on her face and leg. Her rash on the leg looks like fish scale and it turns dark colour overtime. She has them all over her face aseell . Dermatologist has prescribed clearz and MelanoTX. She had been taking then for over an year but it does not seem to help.