Dark butt caused by scabies

Patient: I was 14 years old when I had scabies.Out of neglect, I just ignored it when it was just starting to attack my skin. I finally told my mother and requested a medical help when I noticed that my butt area were already getting worse. Now that Im already in late 20’s, I am so conscious about it because it left marks and worse is it is so very dark. i am a fair skinned woman and it is very embarassing to have a dark butt. Please help me on how to whiten this part. Thank you.

Doctor: