Sorry you lost the fish. It does look like a typical case of Brooklynella tho. It is a common disease on wild clowns unfortunately but effects a host of other fish. 2nd bad part is that it takes a while for it to die off from a lack of a host ( As Mr Todd suggested.) If you have other fish in the tank, your tank will remain infected and any new fish under any type of stress will become infected.
You might want to read the following article: Clownfish Disease - Brooklynella Diagnosis and Treatment
When I was importing fish, I gave all our fish a FW
dip for 1-2 minutes after acclimation prior to being put into the qt tanks. It was amazing how many "things" we couldn't see on the fish showed up at the bottom of the FW
Hope this helps