6 1/2 week old chick Listless and keeping eye closed

[greenkjb]

Please someone give me some advice. Since this morning my barred rock baby has been weak and listless. I have been syringing her water and just gave her some polyvisol. She has eaten a bit of yogurt, mealworms this morning and a good amount of scrambled egg but doesn't seem to be interested in eating this evening. I isolated her from the rest of the flock and am keeping her warm. Her closed eye when she opens it looks healthy. Also, they have been on medicated feed since they were born. Could this just be a weakling? Could it be coccidiosis? So far she has two what look like normal stools, and the rest of the flock have normal stools as well. Any thoughts on what this could be? Her vent looks fine and there is no nasal/eye drainage or sneezing/coughing. Help please! Thanks so much.