It could be the change and maybe just her age. We had an issue with our daughter probably around that age regarding bedtime and sleeping. She would throw a fit as well - to the point she would throw up sometimes. Her daughter said it is ok for the child to sleep with you, but only if you are getting sleep as well. You are not going to be a good parent unless you are well rested.
We too her advice (because we could not sleep with her - she moved around too much). We just kept being persistent (as hard as that was). What we did was insist she stay in her bed. We would begin by checking on her every 5 minutes, not touching her or hugging her and slowly increase the time. It took about a week and then she was sleeping on her own. I'm not saying it was easy and that first week was h*ll with little sleep, but short term pain for a longer term gain.
You could also give your child's doctor a call for advice.