Oh that poor fish is in very bad shape... once dropsy gets that bad, there isn't much you can do sadly. Feeding or no feeding is not related to this condition - it's an internal infection that's causing kidney failure. What you're seeing is the accumulation of fluids. I'm afraid I would recommend euthanizing the fish.
Can you tell us a bit more about your pond? How old is it, how big, how many fish and what kind, what type of filtration are you using? Did you turn off the pond for the winter or is it still running? How do the other fish look?