Maybe try not offering food so often. It might be stressing him out when he really still needs to settle into his home. Try waiting a full week between offerings.

Also...a 10" high enclosure sounds mighty short for an arboreal species, even a neonate. What if you turned the enclosure on its end so that it was 15" high? Of course in doing so, you'd have to give the snake a new week (at a minimum) to acclimate and get settled again. And perhaps offer a mild heat source at the top so that it's a few degrees warmer up high than it is on the floor...and see if he doesn't choose to thermoregulate.