Good luck in finding your snake. You will need to tell him sooner our later, sooner may help in the long run. Kids are so intent on things that I'm sure he would want to help look for his snake. He will probably feel better if you let him help look. When I lost small animals as a child I spent hrs. looking which for the most part meant the recovery of the pet. Mom and dad never had enough time to devote to finding critters. Sending hugs his way and hope he recovers his snake.