DS (6) has had a fever on and off since Monday, full of a cold and also now developed a cough (dry rather than chesty) so I'm assuming Covid 
When do I need to worry about the fever? He's never really ill and in the past the only times he's had a fever it's gone after a few hours. It's been 39 at its highest, but now seems to be hovering round 38-38.5 when it's high but does drop back down to 36/37 when he's not burning up. Apart from the cough and lack of appetite (he is still eating but just grazing and 1 Main meal rather than 3 meals a day but drinking lots of water) he seems well enough in himself. Currently kicking a football round his toy room quite happily.
I've been giving calpol and nurofen to reduce fever as needed, and it does drop a little. But just concerned how long this has been going on for now, I do suffer with health anxiety when it comes to DS too so sometimes I'm not sure if I'm worrying too much