Temperatures in children do respond differently in children to adults. Children spike very high temperatures often regardless of how seriously ill they are because their bodies can't regulate temperature as well as adults can, which is why they also need to be kept warm by us, too, because they get cold so quickly. So they can get a minor snuffly nose and have a temperature of 40°c which responds nicely to paracetamol, then they're singing again.
An adult with fever of 40°c who is feeling acutely unwell must seek face to face medical attention to get treatment or rule out serious illness.
There is no way that anyone here can say that the OP has a cold, is simply "running a fever", shouldn't be concerned, or any of the other dismissive things that have been said, and quite frankly, when you do, you're playing Russian Roulette with a poster's life.
These threads are dangerous, because people will be put off from seeking medical support when they need it, and one day it will turn out that someone had meningitis, sepsis, ectopic pregnancy, a pulmonary embolism, or some other life threatening complaint that was dismissed as a 'cold', 'cramp', 'indigestion' or something else, and they'll quite literally die because they posted here instead of picking up the phone or getting in the car.