Thanks so much for your reply. Francis is a very well loved duck. We are thinking it's an ingrown feather. And we do have a vet who sees ducks, so I guess that's the next step.
Our Drake Pekin duck has a cyst/lump on his torso under his wing. It is bluish in color and is quite firm. It can be moved around a little. It seems to be sensitive to touch. I can send a pic if anyone has a clue as to what this might be. Would appreciate any insight. Thx