I need advise regarding which specialist to use for my 6 year old son which is starting to question certain family issues and people not present, i am not sure who deals with these type of issues, so help would be great! thanks!

Pediatrician or GP: Start with GP, he or she should be able to further advise as to the need for a specialist.

Start with his doc: His doc will likely know someone in the region that can help you both with communicating sensitive issues. A short version is the young at 6 needs simple answers, at 16 they can handle many discussions like an adult. A child behavior specialist may carry many labels locally like medical social worker, therapist, child psychologist, etc.