Yes, that’s exactly it, a feverish non-fever. I also feel a slight pressure in my chest, as if I have breathing issues (but I don’t really). Overwrought also covers it, a sense of tiredness and constant stress without a clear source. Not really aching but still aching. More like a sense that I *have been* aching, the tiredness you sense in the muscles and joints afterwards.
In general a pretty strong »malaise» kind of feeling.
Yup, then I was "asking/guessing" correctly
. Concentrating on the feverish non-fever and feeling overwrought ("tired but wired" I spose is the same): I have this, and have interpreted in different ways, constantly re-checking as ever has brought me to understand and treat it/me better.
Short story: Cold showering helped possible autoimmune aspects, sleeping it off as soon as it came up helped possible insomnia reasons, what remains is keeping a tight handle on overdoing it, best by relishing short moments intensely instead of the speed and amount of activity like I used to.
Long story:
I first imagined it to be something autoimmune, cos it feels like an inflammation all over. So knowing and feeling that cold showering might help, e.g. by reducing cytokines, or simply by sort of reducing the heat, I tried that and that did reduce it temporarily, which seemed to confirm it.
In my second phase on it, the memory crept up on me that it was exactly the same feeling I had in between when clubbing, which was quite OK when I was around 50, but then quickly worsened: Tiredness, screwing all my energy out of my body, giving it all (and that I did, could dance like a dervish, whether Techno, moshing or Mother's Finest live). That put me on to it being a deep need for sleep. And I had been getting tired at 10 or 9 in the evenings, making any evening plans crumble... probably fibro developing. So I worked in a different way on my sleep hygiene, ignoring the advice not to sleep in the daytime, and realized when that happened I could often sleep about 2 hours in the late afternoon, which was better. Gradually I seemed to sleep myself better, and need it less and less and then try more and more to turn the sleep into a nap, and then stop napping altogether, which has stayed that way whatever else is going wrong.
Third phase was realizing that I could have seeming good days with pretty much energy, esp. after sleeping less than normal. When my sleep lab psychiatrist told me that was the effect of cortisol, that suddenly opened up a new realm - the connection to the autoimmune / cold showering, the sleep, the danger of the cortisol ("adrenaline" we informally say) fogging over the tiredness and our needs, plus then the connection (as antagonist) to serotonin, which I could see I had too little of, as GABA was a great help. (As histamine is also an antagonist to serotonin there are similar effects of fake energy thru that too, in the evenings and at 3am, but it doesn't feel as feverish as cortisol, but can come with histamine-y/allergic feelings/symptoms.)
And the 4th phase I'm in now... is ... hmm... probably all of that experience put together, but having strangely got fairly full grip on my sleep since the 3rd jab and much better control of my activity amounts I can usually avoid overdoing it and use it as a warning sign to judge how much I want to continue to overdo it.
So to cut that long journey short, even if to me it was a valuable one: The feverishness and "tired, but wired" is a warning sign that my body is on overdrive, running on empty, and if I calculate carefully and sensibly I need to tone down very soon, and then it'll be OK and worth the ride. But not if I get carried away, exhilerated, get high from the cortisol, sort of addicted. Those are so enticing moments, esp. for someone used to being very active and getting most rewards from it, even believing we are nothing more than what we achieve, that we need to define and prove ourselves by our activities.
My secret to get out of that Speed King car has been to develop savouring single moments more and more. First it seems so boring, but as long as I can be continually active, multi-tasking and task-switching in a slow way, a new type of exhileration and addiction has developed. Yes, it would probably be healthier to just sit and "do nothing", like my wife wishes I would, but I'm just not made that way, so I need my stretches or various thoughts and mind games to keep myself on my toes. When I try to "do nothing", to not get on her wick/nerves, my body very quickly gets on my wick/nerves, with unrest, itching, pain, all kinds of uncomfy sensations, which can make me go mad. So I still need to keep on the move in a slower way. My body gives me no chance to know if it could be any different. And never has....
rather than me. 
