I'm very sorry to hear about that...
Anyway, my best friend did experience the same situation, that was some years ago.
There was one morning, she woke up and shocked to realize she couldn't move, not at all. She laid on bed for a whole week. As I know, she did check with doctors, but the doctors have no idea how it actually happened to a healthy person, and they couldn't find the reason.
A week later, she recovered without any medications, even the doctors were surprised.
I hope your baby's situation is the same with my best friend...hope your baby will be okay after a few days
