Look for an "avian veterinarian" online. Not sure where you are located, but we found an great one in Sacramento, CA. (Dr. Jean Smith) Most regular vets don't know very much about birds, but if you can't find an avian-specific vet, then call as many as you can asking how much experience they have with birds. Most might say sure bring her in and charge you, but not help you or misdiagnose her. Healthy hens usually clean up poop around their vent, but not always, and so you need to clean up big poop build ups because fly's will lay eggs on it and the larvae can travel up inside and cause infections that will kill them (called fly strike). It's not hard with two people, my wife and eye do it after dusk, pick her up with a towel take her in our mud room, cover her head with towel if needed, and trim the whole area with scissors and of course wear latex gloves. It's sounds like you have worms, which I don't have experience with, so I can't really help you there. You can also do a search of this forum for worms, and bet you'll find tons of past posts on the same thing you hen has. Don't wait too long though or she might not make it, or that's been my experience.
