My DD went through a similar thing a few months ago but is nearly 3 so could be totally different thing being so much older. The one thing we changed was spending a bit more time in her room with the lights out after we'd read books etc, and just have a cuddle and quiet talk with the lights out before walking out. This generally worked along with leaving the door open (she refers to it as wanting the door 'whole' open - crack me up), and leaving a light on in the hallway. So for her it was mostly being in the dark I think that bothered her.

Around the same time she was having (I presume) 'night terrors'. She'd wake up after a few hours sleep and really sob her heart out for a good 20min. It would take me a that long to calm her down by holding her. She did this a couple of times just before bedtime as well but thought it was her just playing up so had been disciplining her, which I quickly stopped once I realised it made it a whole lot worse - she would just become hysterical. It lasted for about 2 weeks and each time I'd just take her to the lounge room and give her a big cuddle and not say much because it just seemed to get her more confused and upset so would just hold her and rock her a bit until she stopped.....she'd then pretty much go back to bed with no problems; as long as the door was 'whole' open and hallway light on.

Anyway, I'm sure you've thought of that and sounds like things might be settling for you.