Could it be stage fright?
Oh I remember when an art teacher at school made me sing in front of the whole class.Just like that, out of the blue... Get up and sing!
I was 11... Oh boy, I still shiver when I think of that sometimes. To make it worse, it was only a couple of months since I started at that school (yeah, my family was always on the move when I was a kid, so...)
I remember it didn't go as bad as I thought it would, but damn... the anticipation and the fear of rejection building up... that was hard to break through all those negative feelings.
I guess that what I am tryng to say is... once you manage to conquer those feelings, you'll be fine.