I am a bit new to all this, as I've only felt "dodgy" for 11 weeks, with some decent times in between. My problem is when I feel a decent time -never super but not so bad -I start doing physical things. Or rather, trying to resume at least 50% of my normal life, which before March this year was a very physical life.
So then I start on a little garden task, and that leads to another one, and I'm quite happy and don't feel too bad at all. The exertion (within limits) actually feels quite good for me.
And then the next day I wake up feeling not too bad too, so happily get on with a little more "normal life" (baby steps of hope really) "I'll just go and get an extra log in for the winter." I always have to start doing that in Spring for the following winter, and live alone. Only one log, mind, and that was a pretty thin one.
Thinking "oh that's not so bad, maybe I'm slowly getting better." (?)
That might go on for a few days.
Then a few days later don't feel too good again. Twinges over my eye give me the warning, perhaps a very vague nausea, and wobbly legs in the shower....and a horrible disconnected/detached feeling which is indescribable but is certainly not my usual self, and sheer exhaustion. Eating my breakfast like a robot, can't concentrate on what I'm reading. (At least I can eat -I think. Some people can't. At least I CAN have a shower. Some people can't....
So then I know I have overdone something. I rest more in the day. Usually it doesn't last too long. Yep, I crashed a bit today after 3 days of not too bad. My own fault, I know. But energy came back to a great extent after dinner. Was like a wet rag before dinner.
It does seem like PEM to me. Unfortunately clear and simple payback for physical exertion in my case. I don't have too many mental pressures on me.