Wow... I feel somewhat like this sometimes, too, just out of the blue. Even when I'm completely happy with my life, I get those moments when my thoughts are scattered and I just need to write my emotions down, good or bad, because I can feel my heart and veins I can't get the right words down - you can, and that's a very good thing.
I try to enjoy all of the world and everything good that comes with it. Sometimes though I get too caught up in life and I cry, and get upset, and get angry, and get mean, but I think that's all a part of living - you gotta feel sad sometimes and you gotta feel mad and you gotta be all of the emotions of the world, but you gotta be happy too.