Sounds like your Australorp may have suffered from Heat Stroke or Heat Exhaustion possibly? I suppose you could treat for that and shock like a human. Give fluids, electrolytes as mentioned previously. Maintain adequate body temperature (they may not be able to regulate their own at this point). I think antibiotics are, typically, administered also (but, I'm not really sure, so you should check that out). All that being said, certainly keeping her quiet and resting is a good thing. I hope she pulls through. Keep us updated, please.