Wow... That's a puzzlement.
From what you say, husbandry seems good.
Assuming he was fine before and his water was normal (no surge of chlorine or no one sprayed air freshener over the cage recently).
The speed seems to indicate trauma.
-
One long shot, but you'll never know, is that, although snakes seem to have a high tolerance to inbreeding (more so than mammals), and since albinism (amelanism) is a recessive trait, to produce morphs with traits you can see, some traits internally that you can't see pop up (e.g. weak heart, small liver, male infertility etc.)
I don't now keep but one or two morphs, but when anything mysterious happens to them, I pretty much shrug it off.
-----
Regards, Bill McGighan