It could be meds especially sedative types
Could be a build up of sleep depravation , stress.
I know when I stopped gabbapentin abruptly, it felt like my mind and brain collapsed,
Slurring words , homophone mistakes , sentences tailing off ,

I d think though that typing on this forum does help, its when I try crosswords sodukos that my brain grinds to a halt , its like I can feel it physically .

Plus I know the noise / chatter makes it worse

I've had your brain fog now for a while , but I think it was building up years ago , my last nurse
Mentioned fybromalgia and referred me to a neurologist , do you think you may have this?

The trouble with going to the doctor is that I've had time to think what I'm going to say , so when I go and say " my cognitive functioning is wrong and am having trouble speaking " they can have a false reading.