I don't think the 'FOG' comes from meds, at least not in my case. I have no pain meds, except for Tylenol. I have had FMS all my life and the fog has been my 'buddy' all my life. It has gotten worse as I've gotten older.
I can forget my way while driving, totally lose my destination. I have had to pull over and strain my brain trying to remember where I was going. I make lists for everthing, sometimes just writing things down helps me to remember what I wanted to do or buy. I had outdated notices from work and church that I tore in half and I use the backs of them to make my lists.
I take care of the bills in our house - yeah scarey I know. I can't always write out the checks, I have to wait for the day or portion of the day when my 'math skills' are visiting me. I used to handle large amounts of money and also taught math, you have to know how depressing this is to me. I never used a calculator. Now it is my 'other' best friend - my 1st best friend is still my heating pad.
I can remember the date something happened yrs ago, but I can't remember words I need today. Luckily, most of the ppl I talk to anymore know what I'm talking about and can finish my sentence.
God bless. Alice.