I understand how you feel getting hit by so many bad symptoms must be traumatic and not sure if it's just the body cleansing itself or a sign that you need to stop.
I think that the tipping point is the vomiting. 20 days is plenty. If it were me I'd quit the fast and start it again in a week or so.
Are you overweight if so by how much. If you aren't very overweight then it's a no brainer to stop the fast.