Are your birds standing on wire? If so, that may be the cause of the swelling. Pigeons get painful, crippling infections from standing on wire. If their floor is wire, make sure they have plenty of smooth surfaces to perch on in their favorite places.
Other than that, I don't know but hopefully some of the experts will respond. Can you post a picture? That would be the best way to get some meaningful feedback. If you can't, do a Google image search on "pigeon foot problems" (or something like that) and see if you can find, copy and post a picture that illustrates your hen's feet.
Pigeon feet are important! They can't be healthy without good, strong, pain-free feet.
All best,