Could it have been from someone's (or a couple of them's combs) When i had multi roosters together they used to peck at each others combs and it looked like a blood bath, but combs heal SO fast, so they were always fine. The would of course eat from my white feeders when their combs we bloody and them make them look like a disaster. Im sure you have already looked at this but just a thought..No if I found that, I would cull. Something really wrong there. Everyone looks healthy, no nasal discharge, no vent discharge and nothing in the eyes. Plus they keep running up to me like I have peez dispenser of scratch. The blood was a trail of fresh blood and congealed pellets of blood clots (small) and none of it was on the roost.