Ideally, he should be seen by your veterinarian. Potential infection and pain are concerns that should be addressed by a vet. A rabies booster may also be considered. If a vet visit is not possible right now, place an e-collar (cone) on Simon to prevent rubbing or pawing. Keep the wound clean with a diluted Betadine or Hibiclens solution, being careful to not get any in his mouth. Monitor for redness, swelling, active bleeding, discharge, fever or loss of appetite. This are all symptoms that require veterinary attention. Unfortunately, there are no completely safe OTC products that can be given for pain. Many or toxic to dogs or easily overdosed.