My son started nursery this month and not only does he cry at the door but he cries all morning there. Furthermore, he is also very teary at home or if left with our parents (who he adores and is very comfortable around). He has also been throwing things and hitting too. Also not eating or sleeping well. It's very out of character as he's a very happy and sociable little boy. He has also become very clingy too, especially with me. Do you think this is normal?