When toxins are being removed from the body, they are carried out through the blood. This toxic blood crosses the myelin sheath that covers the brain which causes irritation.
This irritation, in turn, causes the central nervous system to kick on. Whent eh cns is irritated, it can cause "mental disturbances" such as depression, anxiety, mood swings, "brain fog", etc.
You are detoxing right now. More water will help flush the toxins out faster as will regular bowel movements.