Hello,
I cannot confirm anything without examination,but it sounds like pityriasis versicolor.The
white patches of pityraisis don’t
tan on sun exposure. It is a common
skin infection caused by the yeast Malassezia furfur. This skin disease commonly affects adolescents and young adults, especially in warm and humid climates.
Treatment involves topical and oral antifungal medicines.Selsun shampoo(not selsun blue) will be a better idea to start with.