There is no real science behind the use of acv in sour crop . Once the food has sat and fermented bacteria builds. The use of tablets and cream designed to treat thrush are said to help, but the only way to remove the blockage , more often than not, is surgery. Once it becomes a physical blockage only small amounts of food make it down into the stomach and starvation is the outcome. Some people try to Vomit the bird in an attempt to clear the blockage , but this often results in the bird choking. You can watch crop surgery on YouTube. This is one ailment that I think requires a visit to the vet.
Thank you for the advice! I still have a lot to learn about chicken disorders and diseases. For now, my hen is fine. Her sour crop is gone. I will take your advice and take her to the vet if she gets sick again. As far as the ACV, I appreciate the information and next time I won't buy it considering there is little evidence in its favor.