She may have other issues going on. You could try play therapy. Does she have any problems in school or church or other places she is staying? Any other behavior problems? She may be having issues with other kids at the babysitters or maybe with the babysitter. This may be a way she is expressing that something else is going on.
Most kids don't talk out their problems, they play and that's how you find out about their issues. Their play is their work. I would suggest playing with her more. Play games with her, do puzzles with her, take walks, play ball or play outside or play dolls with her. She will open up to you if you do this and continue to do it. We've been Foster Parents and have learned this the hard way. A Play Therapist, basically has the child play with "their toys" (dollhouse, Dr.'s kit, snakes, dolls, kitchen set,etc...) They observe how they play and what they are doing in their play. You can learn a whole lot by what children are thinking in observing their play.
Good Luck and I hope this helps