MikasGirl: My 5 and half month old Barred Rock was exhibiting very similar symptoms as your girls - listless, fluffed up, not eating or drinking, hunched back, comb flopped over, tail down, and green poo. It all started last Friday. I checked out her vent and it didn't appear swollen or inflamed.
After reading multiple posts and doing multiple web searches, I tried just about everything - force feeding her olive oil, honey water, tums, and giving her warm baths. And after watching her not get any better on Saturday, I decided to get some antibiotics. I went to the feed store on Sunday morning, and they recommended Agrimycin-343 to which I've been adding to her water. I had to force the water down her on Sunday, but since then she's been drinking on her own. On Monday afternoon, she ate a little on her own and she has continued to get better - not quite back to normal but not at death's door either. She is still pooing green at times and she hasn't laid an egg in a week, but I have hope that everything will soon return to normal.
I still don't know what is/was wrong with her. eggbound? worms? But what I read about worms, is that the worms don't kill the chickens - it's a secondary infection that kills them. So, although I also bought worming stuff, I decided to wait until she is back to her normal self before worming her.
So don't give up hope! On Sunday, I thought I was going to be digging a hole under the orange trees, but I think things have turned around.