A.G.
Both of my children went through this. I think that it is anxiety. I read a book and i found that this worked for both of my children. Lay her down just like you normally would. If she wakes up go into her room, and let her know that you are there by saying something like, "it is time for you to go sleep now. I will be right outside if you need me." Then cover her back up and leave the room. If she still cries, wait 3 to 4 minutes, go back in and let her see you. Say nothing, but cover her back up, and leave the room. Do that for awhile, and she will eventually go to sleep. My son was harder than my daughter, but when I added some music he was sleeping in no time. It may take a week, but she will get the since that she is safe, but you do not have to be right there beside her to be okay.
A.