ugh, bedtime has become a nightmare

Like the flip of a switch, Violet is all of a sudden TERRIFIED to go to bed. She freaks out when I put her down for a nap and freaks out even more when its time for bed. She makes up a million excuses to not have to go to bed. She's always been my happy-to-go-to-sleep and sleep-through-the-night girl since birth, so this is scaring me a little. She demands me to lay down with her. She uses my first name! She says "Maria! lay down pillow!!!!" over and over and over and calms down the moment my head hits the pillow next to her. If I get up and leave before she completely falls asleep, she gets out of bed and screams bloody murder til I come back. I have to wait til she's completely asleep to leave the room. I can't keep doing this!!