That wiki article was pretty much on the money of my symptoms.
The origins though, I believe, is the trauma I've experienced through my, although short, life. What's more, I bottle most things up, only letting them out in times of great depression. Letting out enough emotion to equalize the pressure slightly, so to speak.
After mulling over it slightly, I've theorized I've just bottled so much up that it's making existential dread.
Still, I'm glad to know that I'm not the only one out there that has felt like this.
Don't bottle things up, that just eats you up from the inside.
You always need to be able to vent. Doesn't even matter if anyone is listening, just vent!
I have a thread I created on another forum specifically for me to vent in. I don't care if I get any responses to it, heckling, argument, or whatever. Thats my little corner of the internet, and I'm gonna vent my frustrations in there, damnit.
Its healthy.
Now of course anything taken to an extreme is bad. Just process things a bit, sort them out in your head, then vent. Don't go on long angry tirades or go berserk and topple masterwork statues or anything like that, but you have emotions. Acknowledge them, express them. Don't even be afraid to cry either. Its all good for you.
Again, too much of anything is bad. Even doing any of this stuff is bad when taken to the extreme. Everything is best in moderation.