I donit think the the white fuzz on the driftwood is the cause of your fishes infection. But, it is possible your fish could of injured itself on the driftwood and caught infection. Is there any sharp spots?
I have fuzz on my bogwood but my crawdads eat it. I have a green sunfish and he rubbs himself against the gravel. I heard its anchorworm so there is no relationship with your fish rubbing themselves against the gravel.