Get off the apple cider vinegar. It is controverisal as to whether it really helps. So it might behoove you to stay off it for a while to see if your brain fog clear up. Drink more water, take calcium and magnesium and molybedenum and pantethenic acid. But many times brain fog is brought on by something you ate that was not good. Either the vinegar or something moldy or possibly try an enema to flush out toxins.

I agree with Remi...stop apple cider vinegar. I tried it for two days and for
those two days I had the worst brain fog I've ever experienced. I think its
due to the leaky gut, caused by candida. I have also been reading about
Pantethine which is a form of the same thing that Remi mentioned. Look it up
on Google. I plan to order some as research shows it helps get rid of brain
fog. I believe they said it makes up part of vitamin B5. I started taking
Vitamin B a few days ago and my foggy head is better! So there must be something
to pantethine/B vitamins