Hi,
i recommend you explain that it is not simply shyness, that you have extreme fear of social situations that is overwhelming you, it stops you from living a normal life, and back it up with some internet articles or links on sa, explain you have a lot of physical symptoms in social confrontations such as short of breath, and at the climatic moment, let on the water works, that'll show them you are not playing games- may not be accurate for you, but gives you an idea.
I remember when i told my mum, i added that i wanted to die, because i can't go on like this. She took me very seriously, and took a day off work to comfort me. When i told my cousin, who is living with me, she never realised it was so serious, though she could tell i was at least shy. She apologised for anything coming across as hurtful that she may have instigated. I poured my heart out, and she ended up telling me how misearble she was, and we wailed into the night lol, it was hilarious, a sadistic comedy, but anyway back to the point, I know you may not want to over worry your parents and family, but its crucial they take you seriously and know the full extent of the problem. Family support is vital. But it starts from understanding your problems.
Good luck!
:lol: :lol: