Sounds like grass clogging up the crop and causing sour crop since he had access to grass but not grit larger than sand. Now we've got something to work with!
I'm not very well versed with emptying a sour crop - I'll get someone else to chime in on this. My forte' is the after care.
Once you get the crop emptied, you'll want to keep her on only easily dissolvable foods for at least a week. What's going on is that green is soured, rotting food. There will be bad bacteria and yeast in there now. What's trickling through the blockage will be mildly toxic and will cause problems for her good bacteria.
So you want to get the crop clean, try to do damage control on the pH and bacteria of the gut, keep the digestive track on mild easy to digest foods while it gets back in shape.
Now's the time for probiotics, apple cider vinegar in the water (to clear up that pH and put more good bacteria in), watching the poop carefully, giving him egg yolks and wetted crumbles and yogurt or whatever probiotic you choose. As an alternative (or in combination with) organic apple cider vinegar, you can use applesauce (I prefer unsweetened) because the pectin will help cleanse the digestive tract and feed good bacteria, the pH will help as well, and it's very tiny, easily passed, and birds like the taste so you can add it to your mixture to get them to eat it. Forgive me if I already said this (I suspect I have) because i just want to get this info back out to you quickly so you can take the next steps.
Let's see what I can get working on the soured crop.
I'm not very well versed with emptying a sour crop - I'll get someone else to chime in on this. My forte' is the after care.
Once you get the crop emptied, you'll want to keep her on only easily dissolvable foods for at least a week. What's going on is that green is soured, rotting food. There will be bad bacteria and yeast in there now. What's trickling through the blockage will be mildly toxic and will cause problems for her good bacteria.
So you want to get the crop clean, try to do damage control on the pH and bacteria of the gut, keep the digestive track on mild easy to digest foods while it gets back in shape.
Now's the time for probiotics, apple cider vinegar in the water (to clear up that pH and put more good bacteria in), watching the poop carefully, giving him egg yolks and wetted crumbles and yogurt or whatever probiotic you choose. As an alternative (or in combination with) organic apple cider vinegar, you can use applesauce (I prefer unsweetened) because the pectin will help cleanse the digestive tract and feed good bacteria, the pH will help as well, and it's very tiny, easily passed, and birds like the taste so you can add it to your mixture to get them to eat it. Forgive me if I already said this (I suspect I have) because i just want to get this info back out to you quickly so you can take the next steps.
Let's see what I can get working on the soured crop.