Hen looks eggbound but it's been 6 days

[boys with hens]

Hi, we have been raising hens in our backyard for nearly three years now. Our oldest hen (a rhode island red about three years old) was walking funny and not eating this last week. I could see her breathing heavy and her tail was down while she walked. She lays on the ground tipped forward a little and won't roost. Her comb looks slightly purple at times. From what I've read I thought she may have been eggbound. We've bathed her, fed her yogurt (that's all we can really get in her) and we currently have her indoors. She's not really making much noise, The smell was awful when I cleaned and inspected her backside, but her vent looks pink and normal. Her poop is runny and almost clear, sometimes there is some dark green in it. I don't know what to do. I'm not really looking to take her to a vet, but I want to help her get better or at least get an idea of what I'm dealing with. She was at the top of the pecking order and the other girls weren't picking on her, they seemed to be gathering around her to comfort her. None of them seem sick and are still laying. Has anyone dealt with something similar or know what the problem could be? My boys are worried about her and I have no answers.
Thanks in advance.