Re: wont sleep by himself
Your son obviously has some fears that are very real to him. I think at his age the only thing you can do is show tough love. Don't go up with him to the bathroom and dont stay with him until he falls asleep. Reassure him that everything is fine, you are just downstairs if he needs you, and that there is nothing to be afraid of. He needs to understand that at his age he has to start doing these things independantly.
If you keep doing what your doing it could lead to problems into adulthood. He needs to devellop the skill of dealing with his fears on his own now or else he never will. I know it will be very hard for him at first but you NEED to stand your ground and stay firm for your child's sake!
If this keeps up and he still seems extremely traumatized after a few weeks of tough love, I would most definately consult a pshyciatrist. Good luck! Keep us posted!