303abuser mate I’m jumping on at this post and haven’t read everything. But if you have ever had covid, a couple of our close friends in their 50s got over it and the fatigue started to go - but what lasted the longest was flashing anxiety which sounds like what you are describing.
It did subside but it took several months and really looking after themselves / getting out in nature.
Ignore me if that’s not what this is about but thought I’d reassure if it is.
CBD oil also helps (12% CBD from Karma Coast)