The swollen eye that she closes a lot might be from mycoplasma (MG,) a chronic respiratory disease. Hers looks “sunken” to me, swollen to you, but they usually have a redness from conjunctivitis. A respiratory disease will make them sleepy and lethargic. You may need to offer water often.
Baytril would treat that—it is probably the most potent antibiotic and treats many conditions, and is banned for poultry. If you use it, make sure to not use any future eggs of hers for a long time, at least a month. Tylosin (Tylan) will also treat MG. If you have the Baytril 10% liquid, dosage is 0.05 ml per pound of weight given orally twice a day for 5 days. It tastes bad, and people report that chickens will not drink medicated water, but to give it orally.
Her eye being closed from a respiratory disease makes me feel better that she may not have Mareks.
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