Please only give him positive reinforcement. Don't spray him with water or growl at him! I'm sure that is very scary for one so young. He's missing his Mama and littermates. Imagine being taken from the only home you've ever known, put in a cage and then growled at and squirted with water when you cry
Poor Baby. He just needs lots of love and comfort, so he'll feel secure.
Spend as much time as possible with him, hold him and make sure he knows he is loved and safe.
Abby lived with us for several weeks before she was ever left alone and even then, she had her big Sis, Daisy to stay with her. She was probably 4 months old by then. I couldn't have left her at such a young age. The first time we left her, we took her to my Mother in law's house to stay while went out to dinner.
I hope it continues to get better....