I hope the holiday was otherwise fun.
The muscles in the trunk are multi-layered, with some responsible for balance and others for movement, which is why you can perform some things without pain but turning in bed is a different story.
I would suspect the pain will go of its own accord, as it does sound like a muscle strain (I once knew a man who triggered a bad back getting a pint of milk out of the fridge).
I'd recommend applying some Atrogel® before bed and before rising and keeping your normal levels of mobility to prevent it stiffening up.
Hopefully you'll have recovered in a week or so.