Thanks ZacsMumme!
She has been an IS really for months. And still is for naps and occasionally at BT. This happened all of a sudden, out of the blue.
They get up at 5:30, nap 9-10 and 1:30-3. BT is at 7. Although I would love a later start we are all up at 6 anyway on work days and the CM is not a fan of capping naps....I had to do some pretty fast talking to get her to agree to this as they are awful when they are woken. Barring illness, they STTN maybe 2 nights out of 3, which I think is amazing!
BT routine has been the same since they were tiny. Supper at 5, then bath at 6, massage, bottle (was BF until a week ago), teeth brushed, story, bed. They have a little light show mobile I switch on. They used to chat for a bit then drop off.
The head banging is something they do in the day too - only against things that make a noise so I've always thought it was just that! Occasionally they have massive tantrums and do it then - more because they are hurling themselves around. It's not rhythmical or settling like that link said, and Z will really hurt herself in her rage.
I'm at the end of my tether. If it was just bedtime I would go with it until she is older, but the NW is stressful and I'm worried she will start to do it for naps too. Our CM is lovely and I really don't want to lose her, but I can't imagine her lying by the cot for 20 mins for every nap!!
Thanks again for all your help!
Liz