I'm also not sure if it's caused by something else. I just really struggle to function and it's a killer. I have lots of projects and life improvement things I want to do, but I wake up and i'm like ughh, I can't concentrate, my brain is very foggy, I have a lack of energy, it's a nightmare and i'm no longer sure what to do about it.
I think my issues might be more related to brain fog, which does come and go, but there isn't a clear trigger and even when it 'goes' i'm never clear at all, it's just a little easier to function, I get a lot of small dull headaches, I struggle to think or concentrate, i'm confused often, my energy struggles, I feel blah about most things and just urgghh...
Lots of empathy for people going through this, as i'm sure others just think you are useless or dumb, when I know i'm trying really hard to be the opposite because those things really matter to me.