Oops sorry; PEM stands for post exertional malaise
It’s a term used a lot with myalgic encephalomyelitis (chronic fatigue syndrome)

The symtoms I was referring to was the flu like symptoms u mentioned of headache, sore throat, etc

I definitely experience all you’ve mentioned so far and am so sorry u deal with it to. I also apologize for my first comment and I didn’t use language that was well received - my brain fog is dementia thick and can make communicating challenging.

I just experience the things you mentioned and I anted to share what I’ve learned through all my research. I wish you relief from it all!