Could Dandruff Be The Cause Of Dark Spots On Back?

My wife got dark spots on her back, from her age 19, now she is 22 years olders. If she took tablet, it would be normal for 6 months and later it comes as she said. After our marriage, 1 year back we consulted a dermatologist, and came to know that it is due to Dandruff. She took treatment and got vanish from the dark spot, even dandruffs. Now again she got dark spots at her back but she dont had dandruffs. May i know why it is happening, and what shall we should follow.