Blurred Vision, White Patches On Mucosa Of Cheek, Syncope, Low BP, Weakness, Tremors, Fever. What Is Wrong?

Hi Doctor,
My nephew has white patches on the mucosa of his left cheek.
Last week he got into the swimming pool and while he was there he begun to feel awful, he experienced blurred vision, syncope, low blood pressure and he felt like he was dying.
My brother was there too and explained that he added chlorine and cleaning agents to the pool and maybe that could have been the reason.
Since then my nephew has been experiencing all kinds of symptoms like weakness, mild fevers, tremors, lost a few pounds and has dark circles around his eyes with white patches along the mucosa of his cheek.