Hi! I have been suffering with this symptom. I couldn’t find my words...speaking was embarrassing. Couldn’t retain info, etc. I convinced my doctor to try adhd meds. I am taking 80mg of Biphentin extended release. It really really helps! Of course it’s not perfect but I have tremendous results.

I think that stress makes the fibro sooooooo much worse, as well as insufficient rest and sleep. Rest is not sleep, it is relaxing and being mellow. If you have not been tested for sleep apnea, go to a reliable clinic and consider a CPAP which is worth every penny if you need it. I love mine so much, I think of it as my pacifier and find myself reaching for it when I lie down on the bed to read or watch tv!!!
In reading other answers, I am seeing a commonality of one form of quiet time or another. If you work, find a way to recharge at lunch or breaks. I went and sat in my car sometimes to get away from the world and being "on". Let yourself be "off" for awhile whenever you can.

I find if I drink water like 1L first thing in morning before even going pee it helps with the fog and gives me a bit more energy. But I drink water with lemon through the day as well. I work in retail and walk lots but used to have a desk job for 7 yrs and still did this and it helped me

I definitely can’t say that I’m fibro fog free, but here’s things that have helped:

1. I have done some of my better thinking while walking from the train to my office. I think movement helps my brain work better. Unfortunately I have a desk job, so usually my brain doesn’t work. :)
2. Meditation: I don’t do it often enough and I don’t do it well, but it definitely helps my focus.
3. Adderall: it’s definitely a mixed bag—I have a love-hate relationship with it and the side effects are annoying—but it can help with focus and make me less sleepy. I stop taking it sometimes especially on weekends or vacation.
4. Restful sleep: I take Lyrica and amitryptilene at night which usually gives me a decent night of sleep. Without okay sleep, I have major trouble comprehending work conversations. With okay sleep, I still have problems but can usually muddle through.

I take a break from thinking and talking and relax. I have found that stress and anxiety triggers mine.