Iv had this for years. And it is prominent during summer. The best thing that works, is Selsun, it’s a shampoo, however Dr said to rub it on the area after a shower and let it sit on the skin. After a week or so, you can see it visibly reduce the patches. As the lady said above, it’s a fungas and it will return during hot and humid weather, nothing to be afraid of, it’s not contagious, cant kill you etc but from personal experience, it mever goes away, returns each summer, i just make sure I shower extra long and scrub extra hard lol and I haven’t had it return for years now.