I agree you probably need to consult an animal behaviorist. Your puppy could just be going through a "stage" in development or maybe he just gets cranky when tired. If you haven't been able to stop this behavior on your own, and have ruled out any medical or underlying problems, that is the logical next step.
One other caution, which you are probably already aware of. NEVER leave a baby or small child unattended with ANY pet.
Good luck, and keep us posted.