Francis, this sounds like PTSD (Post Traumatic Stess Disorder) due to the death of you son. I would immediatley consult a psychiatrist who can prescribe medication that will calm you and also talk to you about the fear that you have. It may of course, not be PTSD, but go to a doctor (not an md but a head doctor), it will help you to understand what is going on and will enable you to help yourself.
Good Luck.
