Hen with Sour crop?

One of my chickens has what I think maybe sour crop.

She has been having trouble for a few days now, has not eaten for almost 4 and is drinking heaps of water, she is gaping now and then and sometimes has foam coming out the side of her mouth. She is still alert and can get away from us easily when trying to catch. I have syringed olive oil the last two nights incase there is a blockage and also a bit of baking soda and water. Her crop feels quite normal with only water inside, but her breath smells quite bad. We have also given aviverm in case of gapeworm. What else can I do aside from taking her to the vet?

What kind of foods should we be trying to feed her if sour crop is the case?

Last night I have done more baking soda and water, probiotic yogurt and a dose of ivermectin under her wing for internal worms. Attached is her dropping this morning. Does anyone have an idea?



She is around 5 years old (Plymouth Rock)

Thanks in advance