I wonder if you are experiencing die off from candida or some other unfriendly intestinal resident. It seems like your dose is too small to cause die off, though, but maybe not. Candida die off definitely will give you fatigue and brain fog, because it releases acetaldehyde, but if you take some supplements to get rid of the acetaldehyde you can probably avoid that. Niacinamide 500-1000 mg, plus magnesium 200-400 mg plus vitamin C 1 gram are three supplements we have found essential for getting rid of acetaldehyde.