Fever is only at and above 100.4
Everything below that is normal.
You have documented the normal physiology of the human body.
It is normal for Body temperature to be higher during the evening and night and comparatively lower during the day time.
This occurs normally.
(Post covid you are hyper alert regarding the way your body functions. This is normal for people,when they recover from a fatal illness.
You are being unnecessarily anxious and linking your throat to it. )
Next Steps
improve diet and take adequate rest.
don't check temperature.
check saturation once a day, if above95 everything is normal.