Fever does not cause brain damage. Fever evolved as a way to fight off infections. It would be pretty retarded if your body gave itself brain damage every time it's fighting a mild infection. Kids get fevers of 104 all the time. It's usually a virus, and unless there you are worried about serious symptoms (certain rashes, intractable vomiting, neck stiffness, abdominal pain, etc.) you shouldn't take your kid to the ER.