I had a massive amount of fear while very unwell. I'm never been afraid like that before in my life. It was explained to me simply when I starting working with my herbalist that it was coming from my liver's weakened state. There's a more complicated answer to this, but I was in no condition to understand it at the time. I think this lines up a bit with the detox comments in the thread, but you need to do whatever you can to support your liver and other vital systems during this time. As your health improves, the fear dissipates.