So should I QT all of my fish for three months? Is there some kind if catch all treatment since we don't know what I'm dealing with?
QTing new fish won't help if a current fish is a carrier.
You could treat the tank with UV or ozone to reduce/eliminate the free floating infection vector. (I use UV) You could still get an infection from fish to fish or fish to rock contact but sterilizing the water column is about the best catch all treatment for a reef.