So, I'm actually not quite sure if this is what I've been feeling, but ever since I've heard of this it seems almost right. I'll try to explain what I'm feeling as best I can, so if this doesn't make sense I apologize. 

I guess I'll try to start with an example. So I'll be sitting in class, whispering to my friends about dumb things and suddenly I just stop talking. Nothings wrong, it's just...I can't continue. The reality of my life will start sinking deep into my chest. I've seen someone explain it as a huge house in your mind, with different rooms holding things such as family, friends, school, etc, but theres also a room with nothing in it. So, as you walk through your house, you accidentally stumble across that empty room, and you become trapped. No one can save you, not even yourself. You just have to sit there and take the boredom in. I think that's pretty accurate. Or, if that doesn't make sense, you could also explain it as a longing for something that was never there. Not wanting to find it, just missing it. Anyways, I'll sit in class like that trying to grasp it, because sometimes it's nice not knowing what's wrong. I can just be innocent for a little longer. It usually hits me as a big wave and wears off after a couple hours or days. I've talked to my therapist about this but she didn't have an explanation for me, so I'm coming here hoping someone can relate.