What symptoms are you seeing? Blood in the droppings can be a sign of irritation in the intestines, and may be a sign of coccidiosis, enteritis, capillary worms, and other things. I would get several fresh droppings checked by a local vet with a fecal test. The signs of coccidiosis which can be common in young birds or older birds with immunity problems, are sleepiness, hunched or puffed up posture, refusing to eat, runny droppings with mucus or blood, and weakness. Corid powder 1 1/2 tsp or Corid liquid 2 tsp per gallon of water for 5-7 days is a good treatment. I would also give the chickens a small amount of plain yogurt for probiotics.