hey Crimson, I'm not under 20 years old either (26 to be exact) but I can relate to what you're talking about. I had my first panic attack when I was 16 and it scared the living **** outta me. I had my girlfriend at the time take me to the emerg. and the doctors came back with a big shrug and a "we dunno" diagnosis.
So, I went on, sometimes I would have panic attacks, I'd get through them, sometimes I would go to emerg and they'd say the same thing. Then they subsided, I still had a elevated level of anxiety but the PAs somewhat "went away". Eventually they came back though. Just this year I've been in emerg a total of 9 times with PAs, this is when I finally got fed up and decided to figure it out.
So, long story short, I went 10 years without knowing what was going on. I'm certainly glad to know now.
Anyway, I'm rambling :|
So, just wanted to post up that most people have their first attack around 15 - 19 but most don't know what it is. If I had the internet then (or if it existed then ;) I would have probably figured it out a lot sooner.
Also, I haven't been in a movie theatre for about 4 years myself. But, not due to PAs, just because I don't really care for them. Weird though that none of us go to movie theatres.