Something is preventing her crop from emptying. So she's trying to jerk her neck around to try to get the crop contents to empty. It's very uncomfortable when the crop is stagnant and yeast may be colonizing the crop, also, causing a burning sensation. Your hen has every reason to feel miserable.
Your vet did nothing to help your hen, unfortunately. Making a chicken vomit is risky and only provides momentary relief. There is a reason the crop won't empty, and that needs to be addressed.
The fluconazole will definitely help. Get her on it as soon as possible. Meanwhile, you can help her by flushing her crop and digestive system. Get some Epsom salt and mix it one teaspoon in one ounce of warm water. Give it to her to drink. If she won't drink it, you will need to syringe it into her crop. Look at the photo below. You want to aim the syringe along the right side of her mouth and throat, sliding under the side of the tongue until you feel the syringe enter the esophagus. The airway is that hole in the center of the throat behind the tongue. Doing it the way I've instructed, you will avoid the airway and the hen won't choke. If she does start to cough when you insert the syringe, back out since you don't have it far enough to the right of the throat.
Get all one ounce down her and do it again later today. Do it again tomorrow if the crop is still not draining. The Epsom salts cause mild diarrhea and will clean out the crop and intestines and gizzard.
