i don't know too much about fish disease. But i do know white spots usually mean Ich, a parasite that latches on to and feeds off of your fish's body. They can be infected for a little while before the white spots (ulcers) start showing up.
I had one clown loach who seemed very lonely. So, we got another one to keep him company.... which was infected at the fish store (i didnt realize till we got home), when we went back, i looked in the tank we got him from, and alot of the fish had spots on them. I didnt want to medicate, but ended up getting "coppersafe". Within a couple days the spots were gone, and havent come back, it's been over a month now. I liked this particular medication because you dont have to shut off your filter, and it says it is safe for scales fish. Anyway... that was my experience. Good luck!