Brain fog is probably better described as cognitive fog. Really is where your cognitive mechanism is fuzzy. So you have trouble finding words, short term memory may be a bit (or a lot) impaired, problem solving is difficult and processing information is slow and difficult. People can experience some of the symptoms of ‘cog fog’, or a lot of them. It may be that during a relapse, cognition is badly affected and then remits. Some drugs can cause cognition problems. I had a very bad reaction to Avonex when I was first diagnosed. But I couldn’t even explain what was wrong because I couldn’t get my brain to work it out, or to explain it to the neurologist. Needless to say, once I worked it out for myself, I didn’t take the drug one week in order to be able to explain what was going on. The neuro straight away stopped the drug! Up until that point, I had no idea MS could do that to my brain. Now I live with it daily.
Have a look at https://www.mstrust.org.uk/a-z/cognition-and-cognitive-symptoms
What helps is writing things down, keeping a diary, writing notes for myself, concentrating on one thing at a time, (no more multitasking), not worrying when I can’t remember things, using a different word when I can’t remember the one I want to use, plus not getting stressed about it. And above all, trying to keep my brain working by using it.
I hope this helps a bit.
Obviously, on the Everyday Living forum, we have a thread called Brain Fog. This is a very long running thread, most of the posters on this thread have experience of the Fog. It’s a tongue in cheek friendly place. And actually, I’m pretty sure it’s helped a lot of us with our cognitive issues as we’ve been quite creative. But, it’s not really the place to go for help or answers, more a place to let your hair down and not worry if you forget things, can’t come up with the right words, or just want to express yourself in a safe environment.