hi, i appreciate your courage of expressing the feeling and need to overcome the issue that you are facing. its natural that at certain age boys will masturbate, sometimes on the bed or in pants. Sometimes in night or in day. In a fraction of time this incidence took place, its not by intention its by chance. i think you need to over come the feeling of guilt and shame. Kindly take the help of psychologist to overcome your emotional disturbance and to handle in better way.
Health Tips
have confidence, try to over come your disturbance through Yoga.