If that white scum kind of breaks apart like you with think Ice might if you shake it "Breaks in sheets". Then it sounds like it may be a lacto infection. I got that once and did not act fast enough and it soured my braggot I was making real bad. I have heard that if you rack it immediatly and hit it with Camden tablets at 1.5 tablets per gallon it should be fine. But you have to catch it quick before the colony of Lacto bacteria gets too plentifull.
A painting says a thousand words. But a painting while on good mead just looks funny!