I'm sorry about your fish.
The two main signs to watch for in a serious or fatal illness are loss of appetite and inability to swim. You mentioned that your fish is still eating and swimming so I would say you are fine for now and can afford yourself some time to work with a few different courses of treatment if necessary. If that changes though, you will need to act quickly.
Oxytetracycline and chloramphenicol are active ingredients that can be found in name-brand medications. They will be #1 ingredient, generally.
Also, remember that Dropsy is generally a disease that is related to water quality so I would advise a large-volume water change of 50-60% along with a complete substrate vacuuming to eliminate any decaying food and waste products that could be a virtual breeding ground for life-threatening bacteria.
Good luck, and let me know how it goes.