This sounds more like a tumor or a cyst. SBD is not a disease by a symptom of poor water quality and/or overfeeding where the swim bladder gets compressed and effects the fishes ability to swim correctly. what your describing sound more like a tumor or a cyst. Bot are not treatable right now. if it burst, and leaves a open wound, then you can treat the wound with antibiotics. Since you have no idea of what kind of fish you have, it's hard to really give good information back. I'll bet its a goldfish. if so, is it being kept in a unfiltered bowl or tank? under twenty gallons? if so, this has all impacted his health. If you can figure out what kind of fish you actually have, we, the community, can help you more.