You might try setting aside some time to go to the park or some other place by yourself--without friends, music or magazines--for a few hours. That will give you some time to get a glimpse into what the underlying issue or issues might be.

If this seems too scary and you'd rather explore this with someone trained to help, try talking to a school counselor. He or she can get much more in-depth in examining the situation than I can.

The good news is that you've taken the first step. I commend you for knowing yourself so well that you can spot a problem and try to stop it before it gets worse. Good luck!