That’s pretty dark. Certainly any parent’s nightmare. The switch to past tense for the last sentence didn’t fit so well.

Pretty creepy – I like it, especially the song.

Pacing feels a wee bit off: the mother would be straight over to the crib at the first sound, rather than hanging around for the song to finish.

Nice work overall, though.

It is a little creepy in a bone chilling good way. I agree with the others about the pacing and past tense, but it does make for an intriguing story.