I'm not sure there's anything wrong with you. We all have days where we feel out of sorts; as long as they don't happen too often or for too many days in a row, I don't think you have to worry about it. If you do find yourself feeling sad or mad for no apparent reason all the time, then talk to your parents about it and see about making an appointment with your doctor. Even though you haven't started puberty yet, your body could still have changing hormone levels as you get closer to it. Make sure you're getting enough sleep and eating a healthful diet; not doing those things can affect mood for anyone.