Son waking up shaking

[LeesaW]

Has anyone experienced this ? My son is anaphylactic to dairy and peanuts. He hasn’t had any allergens at all but three times in the last three weeks he has woken up about 1 - 2 hours after going to bed, comes downstairs confused and then shakes, teeth chatter and says that he’s cold. Sometimes needs a poo then wants to go to sleep. He’s done it once before and vomited as well but that’s the only time. It often lasts about 30 mins to an hour. His temp tonight was 36 deg.
Has anyone ever experienced this ?

How old is he? My 12yo has sometimes woken up like this over the last couple of years. He's quite anxious and it tends to be triggered by worries about his friends.

He’s 10 but I don’t think that he’s anxious or worried