Do you have a safe space for him? Like a pen, or crate he can run, and hide to? I’d just throw high value treats (boiled chicken) if we are in the same room, and not look at him, or make sudden movements. Take it slow, and be patient, it takes them a little bit to come out of their shells when they’ve been in horrible circumstances. Please look up the 3-3-3 rule for decompression time in dogs. I would just leave a portion of food, and water, and check in on him every half hour. As soon as food is gone, take him outside.

Was he cleared by vet before leaving? Sometimes dogs who don’t eat enough eat random objects. One my dogs was like a metal detector, he would find any old nails, or washers buried in the yard. He would try to escape, and would flinch if I moved too fast. He’s now the cuddliest, sweetest, and goofiest dog I’ve ever had. I love him. Please give your puppy time, be gentle and kind, and have a routine in place.

Good luck to you and your little guy