Bulging crops are normal in chicks and often seem unusually large and solid but it is just because they have access to plenty of food and nothing much else to do but eat it and their need for food id higher because they are growing so quickly. I would only take action over their crop if they were not going down overnight when food was withheld or they were acting off.
Bloody poop is another matter. Are you sure it is blood and not intestinal shedding which often occurs around 8 weeks. Intestinal shed will be orangey pink and stringy. Coccidiosis causes dark red blood in the poop and needs to be treated immediately, so it is good that you have done that. I would give the lethargic ones a direct dose of a few drops of the concentrated Corid liquid into their beak morning and evening for the first day to ensure they get plenty on top of the treatment dose in the water. If you have Corid powder instead of liquid, dissolve 1.5 teaspoons of it in 2 teaspoons of water and give the lethargic chicks a couple of drops of that day and night and then assuming they have picked up a bit, just continue with the treated water for the remainder of the treatment period.
Eating the shavings will not be responsible for blood in poop.
