My son has this white circular patch on his cheek. It's not itchy. Any idea what it is and what caused it? How do I make it go away?

Looks like white spots tat are caused by fungal infection. Also known as 汗斑 in chinese. Generally caused by if you sweat and then go to the aircon immediately. Need to see the doctor to get a fungal cream

my son has the same white spots too. But doctor said it just about pigmentation and will dissapear by time. But if you are worried, better check to doctor.