Was she attacked by any chance by her flock mates?
Check to see if there is a wound underneath the feathers, if so you can clean it up and apply some plain neosporin or vetericyn.
The shaking and huddling could be a developmental/neurological disorder or even coccidiosis.
Any sign of bloody poop or poop with mucous?
Corid will treat coccidiosis so you may want to try that. You can treat the whole flock if need be- dosage is 1 1/2 teaspoons Corid powder per gallon or 2 teaspoons of 9.6% Corid liquid per gallon Give for 5-7 days - make sure this is the ONLY water available during that time period. Mix a fresh batch at least once a day.
After treatment is finished, offer some poultry vitamins and probiotics/plain yogurt.
Make sure she is eating and drinking well. If she doesn't seem to want her chick starter dry you can mix it with water/corid water to make a mash.