Earlier in the week i noticed sort of runny poop in the pen. I've been keeping an eye on them, but everyone seemed active. Today, for the first time, i found 2 places with bloody poop and 2 places with just blood. My chicks have gotten nothing but medicated chick starter and any bugs they catch since i've had them. One of the bloody poops was big and round - bigger than a pea, but it wasn't hard inside. All the chicks still seem active. If i check each chick, what do i look for? Bloody tail feathers? Please help.