The biggest advice I have is make some notes about what you want to say. Brain fog being a symptom, after all, it can be hard to remember what you wanted to talk about. So, don't be afraid to write some things down.

Some key terms I've found are - "fatigue, especially after mental or physical effort, that interferes with daily life" and of course "brain fog."

Be prepared to talk about your specific experiences and how this is affecting your everyday life. Don't be afraid to show how this is impacting you. I don't know about you, but I tended to put on my "company manners" with people I don't see often, which makes me look better than I really am. Try to avoid that. Let your doctor see how you really feel.

I'd also recommend checking out the COVID web pages on the CDC and here at Mayo. (I tried to include the links, but I can't because I'm new here.)

I hope your appointment goes well.