Hi My 4-year-old Has Been Fighting A Virus (possibly Tonsillitis

Hi My 4-year-old has been fighting a virus (possibly tonsillitis - there's a small patch of white on one tonsil) for a few days. He's had a temp and been off his food, plus has a persistent dry cough. Vomited a bit this morning, but was actually much brighter today and I thought was turning a corner. I didn't give any painkiller when he went to bed a 7pm as he seemed ok and had had a dose of nurofen about 4.30pm. He just woke there and is clammy and temp just 35.2! However, he is talking and says he feels ok. He did ask for medicine so I gave calpol. Is the low temp anything to worry about? Or is he just cool because he's had a sweat?