Your son received paracetamol just one hour ago, and this medication can take up to two hours to show its full effect. Giving mefenamic acid so soon is not recommended without consulting your paediatrician, as combining these medicines without supervision can increase the risk of side effects. For now, you can help lower his temperature safely by sponging him with lukewarm water and keeping him hydrated. Please monitor him closely. If the fever remains high after another hour or if he shows signs of distress, contact his doctor for the correct dosage and guidance on safely alternating medications.