You have had him for two days- it takes them a while to adjust. With how frantic you sound, one would think this has been months. Take a step back and breath
This is a BIG change for him. Right now, he's absorbing his new family and new environment- it's a lot to take in for a young dog. You're expecting too much way too soon.
How is his crate training? The crate training is key to both the potty training and him dealing with being alone. Your crate is your best friend right now.