I wish I had answers. I can really relate to what you said, though it is not quite that bad for me (yet). It is scary to be divorced from my focus, my drive, my intelligence.

Do you notice that some days are better than others? That is how it is for me; some days, I feel like how I did before the brain fog set in. If that is how it is for you too, then try to get things done on the good days.

Also, see a neurologist to rule out seizures, tumors, and stuff of that nature. I keep intending to make an appointment with one.

You're not alone. This is a very difficult path you've been made to walk. Stay hopeful; maybe this brain fog is reversible.