If you don't see any discharge from the nose/eye and she's acting fine and eating well, a sting or bite from something mildly venomous comes to mind. Insect stings and snake bites can cause significant facial swelling in places like the earlobe and wattles. The site of the sting/bite often is very hard to make out, especially if it's something like a small wasp was the culprit (since it leaves no trace really except the inflamation). In my limited experience, insect stings on chicken faces take a few days to go down while something like a garter snake bite can take a lot longer. I had a hen get bitten on the earlobe by a garter last year and one side of her face was puffy for a long time, including the whole earlobe, part of the wattle, and around the eye. The site of the bite was only obvious immediately after it happened. I found that VetRx helped a little bit with the swelling.