Rest, lots of soothing warm fluids, and paracetamol/ibuprofen, OP - I do hope you feel miles better soon.
Back in February I eventually went to the GP with a really horrible bug (throat, cough and drenching night sweats) I’d had for over 10 days - only because of urging by a worried dd.
As I’d fully expected, he dismissed it fairly airily as a virus, no swab.
That same evening I was hit like an express train with pneumonia, but thankfully only on one side. Hospital hit it at once with 2 different ABs, and it did improve fairly quickly.
I had tested myself for COVID 3 times, all negative, but in hospital they said I’d got it. I still think I had a nasty bug with COVID on top - I’d had covid before it it was absolutely nothing like whatever that bug was.