Meningitis?
It sounds more like it.
But this is a great way to fear monger about the flu.
My son was diagnosed with meningitis when he was 5. He started out with a headache and stiff neck and we had him in the emergency ward that day. Fortunately, it was viral rather than bacterial and after a few uncomfortable days he was fine. He’s now 48.
We might have given a pass on the headache but the stiff neck was the warning sign for me.