DS aged 4 has been happy playing and sleeping in his room until about 4 nights ago. Since then he will not sleep in there saying that the green things come out from the cracks in the corners. We have tried using 'magic spells' and 'monster spray' (water) but to no avail. He will go to sleep without problem in the spare room or my room and will play in his room, just not sleep in there. Other things to add are that he started with a new Childminder last week for before and after school as he started school on Wednesday. Also his dad left us 2 months ago, but he speaks to him every day and sees him at least twice a week. I did check that he hadn't watched last weeks Dr Who with the things in the cupboard. Any advice gratefully received
The monster spray we used smelled of lavender - DS choose the smell. I think that helped because the smell lingers. We also has lots of talks about how it works - led by DS. Apparently it smells like poo to the baddy monsters but the goody monsters like the smell, so help to scare off the baddies. But this was what my DS decided. You will have to help your DS find his own reasons.
But it sounds like you DS has had a lot of changes recently. Maybe he just needs a bit of extra tlc and cuddling for a while until things settle down.