Have you talked through exactly what bothers him? Or got him to draw it? I know you know what started it, but talking about it may help him to bring the fear into the open and make it less scary. And when you know what scares him you can help him to slay his ghosts ('No, ghosts are scared of <insert name of toy>, they wouldn't dare come here' etc)
My DS 3.5yrs has always been a great sleeper from 4 months when he learnt to settle himself, sleeps very deeply, we were very lucky. He woke up only a handful of times before 2.5 then had a few night time wakes but easily settled. Always went to sleep on his own.
Then...watched Muppet Christmas Carol at Christmas time and a few times after and loved it, then 2 weeks ago he was watching it, while I was in next room and i heard a blood curdling scream..........thought he had bitten tongue or hurt himself but he was looking at the screen petrified. A scene with a ghost on a door knocker.That evening as soon as it went dark he started saying he was scared of the dark and could he sleep in mummys bed tonight. Totally out of character. That night he was so upset the only way to get him to sleep was lie with him singing lullabies (quite sweet the first time!).
Fast forward and 2 weeks of this, although last night I managed to sit on a chair next to his bed as he fell asleep. This part, while time consuming and always needing my DH home to have DD while I do this, isn't that much of a bind. But since that first night he wakes multiple times in the night needing us to go back to sleep. Last night was 2am, 3am then 2 more times before morning! It is now a habit but I dont know what to do (head in hands). I am planning to do the disappearing chair at bedtime, move it slowly away, but was hoping after last nights first bedtime with me in chair and not in his bed, that night waking might be better but was worst yet.