House Kept Hen not eating or drinking been 24hrs now - HELP

Ok so cutting to the chase, yep I know chickens live in coops outside but my hen, who's called Chicken decided to move in so she now lives in the house and nap's on the sofa with the Doberman, her best friend Radish.
History: Ex Battery hen, rehomed with family, then rehomed with another hen to young couple who introduced two young hens. The young couple, my neighbors soon had 3 deceased hens.
The young couple when on holiday in July/August 2012 and asked me to care for the hen while they were away. I did. I let her out of her very large run to roam the two gardens everyday. When they returned I continued to let her out; I work from home.
My back door leads onto my kitchen dinner that has a stone floor, chicken would regularly pop in.
When it was cold or wet she would hunker down with Radish in her bed, then as then nights got colder I hadn't the heart to remove her and take her outside to her lonely run.
Anyway Chicken was moved in by Christmas 2012
Food:
She has a feeder with a mix of grit, corn and layer pellets. she has also meal worms most weeks. In addition to this she has any scrapes from the kitchen she wants, during the winter we often ensure there's warm pasta, roasted garlic, rice on hand for her
Exercise:
She has full access to go outside, she pecks the cat flap to go out and to come in.
Every morning she's put outside with Radish while I prepare breakfast for everyone.
Personal Space:
She has a large cardboard box which is lined with towels and blankets where she sleeps at nigh of goes if she wants some space.
He top sheet is changed everyday and the rest every week
Off Colour:
Yesterday she was fine in the morning, I then left mid morning on a hunt for a large low box and chinchilla dust so she could dust bath indoors.When I returned home I saw she hadn't moved from her place in Radish's bed. As the evening progressed it became obvious she was off colour.
She won't eat and we've tried pasta, meal worms, boiled eggs.
The day before yesterday she has been in the garden and had been picking at some grass, she was only picking at the stuff in my hands that I was picking for guinea pigs. I read on this wonderful site about her crop being tied up with a long strand of grass so I followed the advice and she has been massaged and had olive oil - 1 teaspoon late last night (10pm) and we tried again this morning, 12 hours later.
Her comb is a strong shade of pink.
She has a new growth of feather coming through under neath.
Can anyone offer any ideas of what else I can do to make my vip hen feel better? (I have an appointment this afternoon with the vet, they couldnt see us any sooner)

 

On receiving your post i made sure I gave her extra water, not such a bad thing- thank you for making the point i truly believe it helped x.
When we got to the vets after a good exam all that could be determined was that she had a temperature and was defiantly off colour, she's now on antibiotics so fingers crossed things pick up

 

UPDATE:
She's been a lot happier today, drinking, eating though not with a massive appetite she has managed little and often.
Her droppings have gone from occasionally having one with a strand or two of undigested grass to the below. Bright green. They look like she's eaten some green beans, its the best way to describe it.



Her comb seems a good colour, her demeanor seems better but her droppings are alarmingly bright green.



Looking through this site all the related posts have scared the pants of me!!! E-Coli has been mentioned.