20 month old suddenly wont' go to sleep by herself

[Clure]

My DD (20 months) who is usually so good at going to sleep - always stick to a good bedtime routine of bottle, bath, story, song, saying night night to daddy, breastfeed, cuddle and put down in cot with favourite soft toy and settles herself to sleep without a murmur.
Tonight was awful. Soon as I left room she begun crying. Basically it took an hour and a half to get her to sleep (mix of cuddling , laying her down, leaving her to cry - terrible state she got into, eventually gave calpol as wondering if back molar could be coming, stroking head, gradually leaving room) It seemed as if she really didn't want to be left on her own.
She has only been walking a couple of months and over the last few days has taken a few falls resulting in a few cuts and bruises, I wonder if she is a bit fretful?
Also last week has been a little change in her nursery routine (I work 3 days) she is spending part of the time in the toddler room now she can walk. Could this have an affect on her?
Its similar with daytime naps - normally goes down well and 3 of the 4 days I've been with her we've had the same performance even though she has all the signs of tiredness. Going down for naps fine at nursery though.
Not sure whether to go down the cc route, always fought against it but feel I need to do something. Help!