Massive blowout! Poor girl, she'll be okay, but that had to be uncomfortable! Offer them some high iron foods if that happens again (raw ground beef is great and they love it). One of my hens did that once... not nearly that bad, but still pretty bloody. Monitor them carefully for the next month, sometimes this can be a hint of things to come: egg binding, coccidiosis, prolapse, or canabilism. As long as not tissue is exposed, she will be just fine.
I'm completely baffled by this DE consumption thing. I work in a brewery and we used DE as a filtration medium. The bag has warnings all over it about using gloves as it is sharp and can cut skin, and to use a respirator as prolonged exposure can cause lung damage (silicosis). The bag says "Contains crystalline silica and amorphous silica - quartz and cristobalite" Also "This product contains crystalline silica which is considered a hazard by inhalation and has been classified as a human carcinogen by IARC, a unit of the World Health Organization. Possible risks of irreversible effects."(!) I don't understand what possible benefits this stuff might have for chickens (or anyone) when taken internally. I know it's good in the garden as a soil amendment for clay soils, and as a slug deterrent (it cuts them up as they crawl over it). But other than that...
If the blood is from the chickens, then my best guess would be that one prolapsed significantly, either bled spontaneously from the prolapse or had it pecked at to cause bleeding, but it retracted promptly so the evidence is now back inside the chicken.
I'd keep a close eye on them for the next weeks or months but hopefully it was just a one-off.
That is quite a mess! i have had about 3 eggs full of blood over the last few months, but all of the chickens are doing OK and seem to be fine- could it be that she layed such an egg with no shell - just membrane and it burst? that looks like about the amount of bloody mess it would be.
But why consume something that's primary components are quartz and silica? From my college semesters in chemistry, biology, and physiology, all information indicates there is no nutritional value nor can the body absorb these elements.