I have a friend who got traumatized by his first shroom trip years ago. But however, I think the trip opened his eyes and he grew up (something he badly needed because he was behaving like a 12 year old when he was 18...)
Personally I can't understand how the fear could follow you after the trip is over. I've had trips that were total nightmares during the first two hours, but they always turned into the best ones in the end.
And, by the way, I am also a pretty shy person and I have a lot of fears. BUT I think strong shroom trips teach me to deal with those fears. I can now be more relaxed when I start to panick what people are thinking about me and stuff like that. After having had the worst trips of that kind I learned to say "fuck it, I don't care!" and just leave the fears behind.