You make me sick?

I'm going to now write about something that I've only shared with a handful of people in my life. Chances are you'll think I'm full of crap. Or simply not understand. Or think I'm vying for attention. Or, most likely, you'll not even read it, so it won't matter anyway. Regardless, I want to talk about it, so there!
For as long as I can remember, at least as far back as elementary school, I have struggled sometimes with being around too many people. And by struggled, I mean that it can cause me anything from a massive headache, to anxiety attacks, to even physically becoming sick and throwing up. I remember even at my birthday parties in elementary school, some of which had 30-ish kids running around, suddenly getting nauseous and running outside to puke. In high school band, we'd occasionally have field trips to huge competitions with tons of people, or visits to big theme parks like Six Flags or Disney; at some point I'd get a terrible headache and/or sick to my stomach. The local fair has always been one of the worst experiences with it; I have refused to go since middle school. Big shopping days, like the day after Thanksgiving, do it to me; I remember once or twice at a teen going shopping with the family and eventually ending up incapacities; most of the time, I'd buy a book or some drawing paper and go wait in the van. Much of the visiting Wal-Mart does it to me regardless of whether there's a special shopping day involved; I usually just wait until late at night if I have to go there. I remember it happening at the few parties I attended, school dances, or clubs. Even at family get-togethers, like Christmas or Thanksgiving, I've had it - I'll just be visiting, then the headache will hit; I'll try to withdraw until, at some point, I finally have to go puke my guts out and lay down. Obviously, in all of these cases, it makes feel guilty and makes the others involved feel awkward or downright offended. When I go to events with more than just a few people anymore, I simply sit and attempt to control myself - I'll pray, or focus on the TV, read, or even meditate. That way I can make the social appearance and hopefully not get sick.
I've researched it a lot. The most obvious prognosis is that the problem is somewhat psychosomatic. For instance, let's say that, in general, I have a problem with confidence, or perhaps a problem with social environments; so, as a defense mechanism, my body creates these physical issues to give me reason to excuse myself from the situation. The problem with that is that, with friends and family, I don't believe that I -have- a social personality disorder or confidence. At parties, band trips, and family get-togethers I truly -want- to participate! Of course, one could argue that my wanting to be there is a conscious social device, but that subconsciously I would rather not be there, so the psychosomatic idea remains validated.
Another prognosis could simply be anxiety in general; within the last year, I've been diagnosed with anxiety issues potentially stemming back into my youth. There's certainly no question that it manifest itself occasionally the eight years I was general manager for Papa John's. Anxiety attacks are known to cause headaches and nausea, among other things. Once again, it seems that it would have to be some subconscious issue, though, because in -most- of the above circumstances, I -want- to be there! My anxiety episodes which I have consciously recognized have often been related to organization problems, being late, feeling inadequate, etc. But never around my friends and family! So again, it's possible that that's the issue, but it still doesn't sit right with me. I can't recall, as a musician who's played countless weddings and luncheons, numerous solo performances and rock band performances, school band solos (not to mention that I was the only synth player in the school band, making me stick out pretty easily), and piano recitals, ever having had the anxiety, headaches, or nausea; if anything, I'd have the typical butterflies and sweaty palms that everyone experiences at some point. Heck, I even commandeered (more like my friend Gary commandeered for me) the piano bar one night on a Caribbean cruise ship, playing for over an hour for the dinner crowd, packing the entire room, and taking requests!
So, when viewing the previous couple of potential prognoses, it doesn't really add up.
Then, there's the "new age" concept that I read about once that might truly explain it; I'll save that for tomorrow.