The correct reason has to be found out and worked on. You may sit with an adult you trust and talk to him/her. If still doesn't work, consult a Counselling Psychologist and discuss your history. You will certainly be helped.
Next Steps
Discuss your problem with a trustworthy elder. If that doesn't help seek professional help from a psychologist.
Health Tips
Try praying and meditation. Remember you have a very powerful mind. Keep it nourished with positive thoughts.