You don't give any examples of why you feel you are mentally disturbed, so I really can't tell you. However, you should do a little research on puberty. It will help answer some questions you have on what your body is going through, and what your emotions are doing to you right now. I've posted a link I think would be helpful for you.
If you can provide some examples of what you're going through, I'll try and help, but as your question stands, it's impossible to guess.