Do you know his medical history? Loads of, apparently, heathy people drop dead from undiagnosed conditions. Being completely exhausted was probably one of them.
One definition of “flu” has always stayed with me and that is; “If you are in bed and there is a £50 note by an open window which could blow away, without hope of retrieval, and you can’t be bothered to get to it, then you have the flu” Anything else is a bad cold. What any strain of flu does...
I had my car professionally detailed a couple of years ago using GTECHNIC which cost about £700 and took two days. All the swirls were removed and the coating applied. Water just beads and runs off. Expensive, but worth it in my opinion.