I have an 11 month old dd and she was a great sleeper to start with. She is FF and dropped night feeds v early, I think around 8 weeks. She has always been good at self settling, I can put her down in her cot and she will drift off herself.
My issue is she just will not sleep through the night. For a good few months she would wake anywhere from 2-8 times a night crying but just for her dummy and would go back asleep again no problem.
The last few weeks/months (I don't even know when this started now!!) she has been waking about an hour or 2 after she goes to sleep and is hysterical, will not take her dummy etc. It sounds like she is in pain but then I bring her into our bedroom and lay her down and she settles straight away and is happy and wants to play. Once she's calmed down I manage to get her back into the cot and asleep but this takes at the v least 30 mins. She can then wake numerous times during the night, I try not to pick her up, just rub her belly, shush her etc but she gets hysterical. I then end up brining her into bed with us.
Last night she went to sleep and slept through until half 6! I was estatic! But tonight it's back to normal 
I've tried changing her nap times too but day time sleep doesn't seem to make any difference!
Can anyone offer any advice? We are lucky in that we have loads of family around who would babysit and I would love to go out to the cinema or something with my husband but I can't leave her when she's like this.