Corid is very safe to use, even if they don’t have coccidiosis. Seeing intestinal shed or some red repeatedly does seem like Corid is a good idea. At their age, they are building up a tolerance to coccidia organisms in the dirt and in the poop. I would use Corid liquid 2 tsp or powder 1.5 tsp per gallon of water for 5-7 days. Do not use B vitamins during treatment.