He is pretty thin and looks dehydrated. There are very few hatchling babies that are small enough to need pinkies. I would find some fuzzies or even hoppers if you are getting mice. You want them to be a little thicker than the snake. You also don't want to overload his system by feeding him more than his body can handle. If he does fine after this feeding, try feeding him something about as thick as he is every 3-4 days if he will take it.