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.