A couple days ago, 2 of our roosters started limping. Then a third started limping and a hen couldn't stand up. The roosters don't seem to be getting any better and we put the hen down because she couldn't move. We're worried that we might have Marek's in our flock. Our chickens were all hatched this spring. Some we got from a hatchery and we had them vaccinated for Marek's. The others were from the feed store and 2 different individuals. Is there anything else that could be causing the chickens to limp? And are there any other symptoms for Marek's that we should be on the lookout for? ETA: Just realized that there is moldy hay in the coop. Could that somehow be causing the limping?