That sucks, Brinny.
I'm assuming he was in your 10 gallon tank, right? How are your water parameters? Dropsy, while seemingly random, can often be attributed to water quality issues.
It looks as though maybe you've pushed the stocking limit a little too far, based on what's listed in your sig. Might be time to do a more frequent water-changing schedule.
Or maybe your tank is perfect and it was just crappy luck.
Big Vine