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.