What is wrong with me?

I am fealing really weird in myself and I know alot of reasons why but I am really not sure. At the moment I am doing exams two years early (I am 14) and I don't see loads of my parents but some times I suddenly feel awfull, like there is no point in life and I leave class and go to the loo's and cry but I don't know why which makes it worse. I think that really I feel like that all the time its just most of the time I am just trying to make people think that I am great so I try to act really hyper. Recently though when I get upset which happens a few times a day i have started scratching my hands really hard so the skin comes off like carpet burns. I have loads of scabs now and my hands look raw and people keep asking me what happened. I am not even sure why I do that, I just did it once and now it seems to make things better. I started saying that I just woke up with it but then it seemed like people were getting suspicious so i said it was carpet burn. I can't tell my parents because I feel like I have to be better than my siblings, I don't know why but that pressure is there. I also know that they will just think it is attention seeking. I want to stop and I have tried and still am but I can't. Everything is turning into a lie, me pretending to be happy, my hands, how I feel and some times I wish I would get caught so I could talk to someone but I know that that will never happen and even if it did I would just lie my way out of it because I don't want my parents to know. That is why I have this account, because its the only way I can tell anyone. What do I do? Am I pathetic? Am I depressed, or is it stess or just hormones? I need advise :(