I really should invest in a poultry medical book.
It would make doctoring so much easier me thinks.
The symptoms you described sound a lot like a finch I had many years ago. You might want to isolate your hen and try to get her to stop laying. When I said egg bound it doesn't necessarily mean there is an egg stuck in her but rather having trouble laying. She could have an infection in the egg track or her bowls its hard to say.
But my thinking is that to get it to clear up she'll have to go on hiatus from egg laying for a few weeks. The feathers sticking up, not laying flat sounds like swelling to me. If you said the whole bird was like that then she definitely is sick.
Not liking the sound of poo sticking to her rear. I'd start with a fecal sample sent to your vet if he's willing to do one. If not then give over the counter water soluble antibiotic found at your local feed store or pet shop. I do not recommend eating eggs from her while she is being treated.
May your troubles be less, Your blessings be more,
and nothing but happiness come through your barn door.