Hi my son 5 came home from school complaining of a headache. He didnt have a temp but give him some paracetamol. He then started crying and refused to eat his dinner and just went to bed. When I checked on him he was still crying abd went to the toilet. He then was sick and very sweaty but cold. Complained of feeling cold although was very sweaty. Went back to bed and was sick again. 20 mins later no sweating he is now asleep and sweaty but cold to touch. Is this something serious ?? Thanks