I always thought that brain fog was that sort of state that one walks around in and it feels as if there is a dark cloud hovering over them... sort of like a Depression where everything is blah and sort of grey... you have trouble concentrating and all that...
Brain farting is when you're forgetful and lose your train of thought...?
Do you ever feel foggy, like the world is grey, all food tastes the same and you've lost interest in things you used to enjoy?