Dropsy is a disease of the fish's kidney's and the primary symptom, bloating, is attributed to the fish being unable to expel water from its body.
The medicine you have been using, Acriflavin, is appropriate for cases of dropsy so the only other thing I'm recommending is that you seperate the fish, in a quarantine tank, and add some Epsom Salt to the water at a ratio of 1 teaspoon per every 5 gallons/20 litres of water. Epsom salt has the capability of drawing out the accumulated fluid that the fish is retaining. Try this for 14 days doing intermittent 25% partial water changes every 4-5 days whilst adding the corresponding amount of epsom salt to the new water only.
Just to confirm, when you administered the Acriflavin there are a few things that should have been done and they are remove any carbon there might have been in the filter media as carbon will effectively filter out the medicine and deactivate the UV sterilizer if there is/was one present in the pond during treatment.
Best wishes and please let me know if you have any questions.
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YOUR TROPICAL FISH RESOURCE
OVER 20 YEARS EXPERIENCE W/TROPICAL FISH---BREEDING, MAINTAINING, CURING