hi! This is my first round of chicks so brand new to everything! I have 8 chicks about 4 weeks old. All we're vaccinated for cocci and mareks, and I have been feeding them non-medicated feed per hatchery instructions. A few days ago I noticed some blood in their brooder..I didn't see any wounds on chicks, and as far as I could they'll at the time it didn't look mixed in with the poo. For the past week we have been keeping them in garage at night with a heat lamp, and in their coup/run during the day since weather is great now in socal. Coup is brand new floor is covered in sand. This morning I noticed a bloody stool. Chicks are acting normal eating, drinking and being curious. I'm not sure which chick left the suspect stool. I've only seen 3 of 8 poop and all look normal. Could it be cocci even though they are vaccinated? Any recommendations on what I should do? I would hate to loose any of them! Thank you!