I also always considered "brain fog" the inability for me to think straight or my forgetfulness, cant find the right words, forget what I am doing or going, etc. that is totally unlike me because my brain is normally overactive and always had a photographic memory. For me, I feel dizziness is when I feel the room spin, I feel off balance, feel like I am moving when I'm not.....those type of things. Of course dizziness caused by lack of blood and/or oxygen to the brain can make me have both at the same time and maybe this is what you are having so it can be confusing. I have only noticed itchiness when I am standing and the blood pools in my legs, sometimes it makes my lower legs or ankles itchy but it resolves when I lay down. Also sometimes feels like a bug crawling on my leg when there is nothing. I always assumed it was the blood flowing down my legs or maybe my veins but dont really know.