Head bobbing Chick

[cuzifit]

I have a chick about 8-9 weeks old,who is having a problem holding up her head and seems to be unstable. (like she's drunk) I have isolated her.Any ideas? I'm new to chicks. Have given her yogurt and added apple cider vinegar to her water.

 

[cuzifit]

Just a added note: she is eating, & drinking. No blood in her stool.