It seems that you may be having most probably tinea versicolor
It is caused by yeast ...melassezia furfur.
Antifungal tablet like ketoconazole
for 2 to 3 weeks may be taken.
Antifungal cream like ketoconazole cream may be applied.
Antifungal shampoo containing ketoconazole may be done.
I think you might improve. However, you consult dermatologist
I hope you got my answer.
Dr. Ilyas Patel MD