I hope your hen is doing better. Has she layed yet? I had a hen who had issues with being egg-bound. If you look at her vent, you can see it pulsing (for lack of a better term), which is her trying to pass it. You can also feel the egg through the skin below the vent.
If you want to go the vet route, St. Mark's Vet has avian vets. They definitely fall to the parrot end of the bird spectrum in terms of care, so I think the advice someone gave earlier about asking about tests and talking about how heroic you want to be is very good. The hen I took there was very special to us. The bill came to $300, just so you know.
I think it is fairly uncommon for hens to be egg-bound though.
Best wishes. I hope she feels better.