At this age, Coccidiosis is one of the more probable causes. It causes droopiness, sleepiness, lethargy, lack of appetite, and sometimes bloody droppings. I'd get some Corid as soon as possible, and start treatment. The dosage for Corid liquid is 2 teaspoons per gallon of water, and the dosage for Corid powder is 3/4 teaspoon per gallon of water. Give Corid for five days.