baby sleeping

My LO will only sleep on her belly on my chest. The second I flip her over or put her in her bed she wakes up and is fussy. This is new within the past few days because before she would sleep in her rock n play. I'm out of ideas. I know she's tired because she'll be awake for hours during the day, but she just won't sleep. I'm at the end of my rope...I'm also a single parent, so she relies 100% on me for everything...