It is most likely a combination of flu shot reaction - statin myopathy and hives. But the symptoms didn’t start until the flu shot. Not everyone has a bullet-proof immune system.
I have a very poor immune system, have for years. So I don’t get vaxes, and try my best to stay away from people who might be sick, or groups of people, during flu season.
I feel really junk right now - turns out a friend I picked apples with the other day may be sick.