Over the past month my almost 2 year old has radically started fighting sleep. For almost 2 years we've been able to lay her down in her crib for both naps and bedtime. Out of the blue she's started screaming at both times consistently, and more recently, all through the night. Because of this, my 3 year old hasn't been able to nap for the past couple of weeks, and the only sleep I got last night were the two hours I slept on the floor in her room. The only way I've found to get her to sleep is if I'm in the room with her. I have no idea what prompted this change. We have a regular bedtime routine, and she does not seem to be teething. What can we do to get good sleep again?