Looking back at my social anxiety when I was younger it seemed to me to progress over time something like this:
1) Fear of negative outcomes from socializing (e.g. being humiliated, insulted, or cast out of social circles) caused any social interaction to be a painful experience.
2) Although the fears were hardly ever realized the pain was remembered and thus caused additional anxiety during the next social experience.
3) This new pain was again remembered and there was an additive effect as each historical painful social experience contributed to all the subsequent experiences. Like touching a very hot stove, the pain experienced from touching the stove caused me to withdraw from further contact.
Ironically, I believe the best thing for me at the beginning stages would have been to have my worst fear realized (complete and forced social rejection) so that I could have learned at that point that a new life can be built through my own efforts unreliant on other peoples' opinion.
That would have allowed me to fear each social situation less and thus the stovetop would not have felt so hot, so to speak.
Can you focus on what exactly it is you fear rather than on the fear itself? I don't know if this long post will help or if it would have helped a younger me but I thought I would throw it in anyways. Good luck!