@Marylib over the past couple of days my wife seems to have returned to her pre COVID state (although hard to tell because her MECFS symptoms vary a lot throughout the monthly cycle). Her recovery was relatively unidirectional.
For me, I've had a bit of a rollercoaster ride, got better then worse then better then worse now getting better again. Was at work from home full time but I've dialed it back. One day I went into work and it was awful, set me back.
At the moment I am working from home 4 hours a day spread across 8 hours with lots of breaks, including eyes shut rest. I have some symptoms in common with MECFS but I imagine that's just because some MECFS symptoms are just the symptoms of being sick.
If I exert too much physically or mentally I feel nauseated, get a fever, get brain fog, spacey feeling, stiff jaw, pins and needles in my scalp, tinnitus. The greater the complexity of my mental exercise the sooner I feel sick, and I also find conversations drain me quickly, especially if I talk energetically. And, on the couple of days I sued more than my energy quota I felt worse the next few days (hence the rollercoaster).
so it seems in someways very similar to MECFS except compared to my wife I don't have orthostatic intolerance, (most of the time) I don't have unrefreshing sleep, and I do feel normal at times whereas she never does.
I think as long as I can keep improving, rather than going on a rillercoaster, I should end up fully recovering.