She sounds like a genetic fluke (I've only heard of this one other time) where she was laying 5 eggs a day.
As mentioned above, egg laying takes a lot out of them as far as nutrients. It's very likely that her body couldn't handle the number of eggs it was generating on a daily basis. So the nutrients her body needed in order to survive went into eggs instead.
It also could've been an internal issue such as being egg bound, or some sort of egg production issue where she got blocked from eggs trying to pass to quickly.