Help needed, wyandotte with sour crop, and very weak legs.

[estgus12]

I have a beautiful silver laced wyandotte who has had/got sour crop. we have been treating her for the past 3 days with probiotic powder, and feeding her a scrambled egg. All our chickens have been getting an oats, live youghurt and garlic mix. She is doing better, eating, drinking, making some noises, moving around. However, she has very weak legs, can't stand too long, can't perch, can't run (she tries now and again, but just tips forward). I plan to take her to the vets if there is no improvement tomorrow, but was wondering if there may be something we've missed. The others are all fine, so there I'm certain its nothing infectious. i would prefer to avoid the vets due to the cost. Our chooks are primarily for egg laying, so its not particularly economical if I take her to the vets (and likely to be very expensive) Would love any suggestons people have (I'm in Australia)