I have a cold, it is only a cold but I feel dreadful.
With most colds, I agree, you can more or less carry on as usual. This one has me barely able to keep my eyes open, I'm alternating between feeling freezing and sweating, I'm hungry but I can't think of anything I can actually face eating. My whole body aches and the pain behind my eyes is incredible. I have a cough that hurts my chest but worse, every time I cough, it moves my head!
This is a go to bed until it's over cold IMO but my parents are due here for tea and my mum doesn't "do" illness. I don't remember her ever taking to her bed unwell.