I'll say that time is of the essence.
Chickens are remarkably good at hiding illness or problems, they will fake eating and drinking as well. Most times when you start noticing them feeling bad, they are well on the downward spiral.
That article was fine until they got to the part about forcing fluid out of the bird. That is something that I/we would never ever ever ever do. Its far too easy to cause them to aspirate, especially doing it multiple times a day like they suggest. If they aspirate and don't drown you wind up with pneumonia and they die. IF I was in a position that I had to go that route, I'd be more inclined to use a tube and syringe to slowly draw the fluid out rather than force it out and risk aspiration.
Most of the time an impacted or slow crop is what leads to it going sour, massage, coconut oil, and some other things can be the answer to get them going again.
We treat sour crop with Monistat and any other treatments happen at night or early morning to reduce stress on both the sick bird and the flock. They are far more docile in the dark.
After 2 weeks of trying every other sour crop treatment with no signs of improvement, I got desperate and tried something unproven. After learning that sour crop is a form of yeast infection and reading that some others had treated with Clortrimazole (found in Lotrimin and Mycelex) , I decided...
www.backyardchickens.com
www.thehappychickencoop.com
