The implication being there is no discernible transition between perfectly fine and full-blown cold? You're just trundling along, enjoying your day, and then - BAM! - like a ninja, it's there?

Or are you saying it's too difficult a diagnosis to make without professional support? "What's wrong with you?" "I don't know, my nose is starting to feel a bit weird and my head feels a bit stuffy.".........."Just back from A&E and would you believe it's a cold!" "No!"

Yeah thought not.