A sick minded person aka a sicko or sick fuck (doctor in their own right) who specializes in counseling & advising other sick minded people (sickos & sick fucks) as well as the so called "normal" minded. Guiding people through really sick shit more successfully, in most cases, than the Psychiatrist your doctor will refer you to.
A doctor (specialist) who is sick minded and counsels other sick minded people, who having by life experience learned enough about the sick mind & related behaviors that no school degree is required.