Hello! My child is 3 months old. His temperature has been rising sinc…

Hello! My child is 3 months old. His temperature has been rising since yesterday, at 37.5. I gave him Ibuprofen, after which he sweats profusely and the fever disappears. What could be the cause? Is it because of a cold? There's no cough, only a temperature. Has anyone experienced this? What else can we do? He doesn't suckle, he doesn't want to, and even formula isn't working. We're on mixed feeding.