I have a teen cousin who is sick with a rash all over her body. Has toxic shock come back?

Never gone. You have not given much information but sick with a rash your cousin should be seen now.
Not the 1st thought. Common things are more common. There are dozens of viral and some bacterial illnesses other than TSS that produce fever & rash in a patient. TSS patients are usually in coma rather quickly after disease onset. If your cousin is just sickly with a rash it is likely something else.