Your case is really interesting. Did you find any injury
due to some pointed object / some foreign body still left inside the wound?
Please visit a pediatrician
as soon as possible.
You have not said about the amount of blood coming out. If it is severe, your child needs urgent hospitalization.
However, bleeding for 8 hours is exceptional. It may be due to bleeding diatheses (An abnormality in blood clotting system). So, get him examined as suggested by your doctor.
Do not delay, it could be an emergency.