I have been using Retin A for about 3 weeks. Two days ago I noticed a darkening around my temple and cheek area on the right side of my face. The nurse at the doctor's office did not have a clue. She suggested seeing the doctor. My co-pay is extremely high to see a dermatologist, especially if this could be resolved by simply speaking with him. Is this darkening normal or did I fail to use enough sunscreen?