I hear ya, ShyGirl.
I've started drinking a can of Sugar Free energy drink (lidl - 29p per can!). Same effect as coffee, but tastes nicer. I've never needed this in the past (and I actually considered that those that did drink coffee were 'cheating'!) - but it's definitely helped me.
Getting BG down also helps with lifting the fog.
The good news is, it's not a one way street. You can get your old brain back! (Thank God!)
Sounds like you may need a med review, too. What are you on?