Why do I feel so depressed at random times?

Heh. I don’t understand why at some times I feel just wrong, for no reason. I guess I feel depressed, and then it goes downhill and I start being so lonely and desperate even tough there’s no cause to it. I always end up having that really stupid feeling that if I hurt myself, it’ll be better, yet I try not to do it, because it is so stupid. I don’t know what to do about it, and even though the logical thing is to talk about it, I just can’t. I’m shy, I guess, but I really can’t talk to people, it’s silly, but I’ve somehow, after thinking about it a lot, got to the conclusion that I’m afraid of them, because around people, I always feel like when I was a little kid and I was afraid of being left alone at home. I know this sounds terribly silly, but it gets to the point of me panicking instead of behaving like everyone else. Anyways, sometimes I am also really happy for no reason. I just wake up and am happy all day. It doesn’t make any sense to me. I know I should go see a doctor, but I know he/she will prescribe me pills, and I am afraid because, if those pills change how I feel, somehow, won’t they change who I am? If anybody that reads this has already taken those kinds of pills, please, tell me, did it change you? I love writing, will it change the way I write, the way I feel about it? Will it change my way of understanding and seeing and sensing the world around me? If it does, what happens if I were to stop taking them? Will it go back to how it was before or worse?