My thought on the one that started bleeding a few days ago. She may have started the birthing process and something went wrong, causing most of the babies to die?

Did she give birth to a bunch of dead ones, or did you only see 4 total come out?

PS Ive had females bleed some for up to a day before giving birth. It isnt the common occurrence, but of the few times Ive had it happen, they all gave birth fine.