Behind the door? Brilliant!
Sometimes moving him works. We don't always try because we're so tired that the potential of more angst puts us off. To be fair, that is a very unusual night. Thank goodness.
With the benefit of daylight and coffee, I can be more understanding. He's just been moved into a new room at nursery. This, as well as being the third nursery room in 2 months, is a big move from upstairs with the babies and tweenies to downstairs with toddlers and preschool. It's busier, noisier, etc. He has shorter naps there (they've halved). Drop off used to be easy. Now he sobs when I leave.
For DS, his world has changed massively. He will settle again. I just hope it's soon!