High fever and blue nailbeds

So my little boy is 10 months old, he’s had a high temperature since Saturday. Last night and today his temperature is peaking at 40 degrees, and barely dropping below 39.5 with calpol and ibuprofen. He’s not his usual self, just wants to sleep, doesn’t want to be held by anyone other than me, and now I’ve noticed his toenail beds are blue? Should I be worried? I’ve called our gp but they won’t see him and will only call after 3pm, not sure whether to skip them and go straight to 111?