Yesterday afternoon we let our 5 1/2 wk Buff Orp & 6 1/2 wk BR run around in the coop with out 9 wk EE. We have been keeping them in brooder box due to colder nights & pecking by older EE. This morning I noticed what looked like a bloody dropping in the box. I cleaned the shavings out of the box & gave them yogurt & mixed some DE in their mash. Noticed 2 more bloody looking droppings over the following hour. But have only seen "normal" droppings in the past 2 hours. Last week the same thing happened after letting them run in the coop for 1/2 day, but because I was afraid of losing one or both chicks, I gave Sulmet in the water for 2 days & haven't seen any problems until today. We have only had them 1 week and not sure if they were on medicated feed from hatching or not. The breeder had them in a brooder box w/ mesh floor. Have never seen dirt or grass until we introduced them to it last week. They have been on med feed for the past week (since last incident). In our coop, though, they were snacking on grower mash, grass & whatever else they pecked at. They seem fine otherwise. The cool breeze outside makes their feathers look a little ruffled so it is hard to tell if that is a symptom or not. Cocci? Ate something disagreeable or new? Stress from new surroundings & being pecked at? Would love to integrate all 3 chicks in the coop soon. Worried why this happens each time they try the coop out. I appreciate any helpful advice.