Hi Syllie
Social phobia is also called social anxiety. It can be triggered under certain circumstances. Think about the very first time that you had this feeling. What was going on in your life at that time.
I suspect also that there was an authority figure in your past who scared you and now when you come across new authority figures that anxiety gets triggered again.
A properly trained hypnotherapist with a qualification in NLP would be able to help you
National Phobics' Society - NPS Home Page they treat these conditions every day.