Coincidental EYP in two hens in two days? Or do I have a disease?

Lost my seemingly perfectly healthy 22 wk old Black Sex Link on Monday after a day of no eating, very little drinking, poop that looked like pale yellow egg gook with blood in it, lethargy. The vet had no concrete idea of what was wrong, but the only thing that seemed to fit was Egg Yolk Periontitis. But now my 22 wk old BO is exhibiting the same lethargy, no interest in food or drink and pale yellow poop with blood streaks in it. Can it be that they both have egg laying problems and its just a coincidence that it was within 2 days of each other--or do I have a nasty disease that may take over the rest of the flock??!!
HELP!