Yes, chickens can starve from crop disorders. It's why I don't recommend withholding food while others seem to be in favor.
Yes, do the cooconut oil, but don't massage.
Yes, start treatment with the miconazole immediately. There are several methods of treating crop yeast. Medistatin, copper...
Giving the coconut oil is a very wise place to begin. This article I wrote will fill you in on what else you need to do. https://www.backyardchickens.com/articles/how-to-treat-sour-crop-and-impacted-crop-and-how-to-know-which-one-youre-dealing-with.73607/
Worming often does cause dead worms to...