We went through a similar issue and the doctor said it could be nightmares. She also said Ava had to learn to deal with them on her own. If she woke up in the middle of the night we were to wait 15 minutes before going in to check on her. Most nights before she reached the 15 minute mark she quieted down and fell back to sleep. Rarely she cried beyond that time. I'd go in and hug her, sing to her, or rub her tummy/back...all without lifting her from her bed. It is key that she still was in her sleeping space. I never stayed longer than five minutes. I always said, "it's sleeping time." Then I'd leave and try another 15 minutes. It may take a few nights, but if your daughter was able to sleep through the night before, she can get back in the habit now. Good luck.