My two year old son who only a week ago was happily saying goodnight mummy then singing himself to sleep, now screams when I try to put him down swing mummy, I want mummy. He then wakes up in the night which he never does and won't go back down, clinging onto me. I have resisted taking him into bed with me and keep him in his cot. Why this sudden change, how do I get my good sleeper (albeit early waker) back- help !!!