Some of the meds used to treat Gill Flukes are Clout, Fluke Tabs, Paraform, Trifon, Paragon, Quick Cure, Formalin, and Jungle Parasite Guard. I'm not familiar with the med Life Bearer so I can't comment on it.
Is the fish rubbing and scratching against things? Breathing hard? Would you say the white substance is slimy? Fuzzy? Bloody? Is the area around the gills red? Is the fish eating? Swimming normally? Hanging at the top or hiding?
I understand your concern that you don't want to treat until you know for sure what the fish has. The problem is that unless its something very obvious, without taking an actual sample of the white substance and looking at it under a microscope we're not going to know for sure. I can't tell anything from the pictures other than to confirm the fact that there's something white there.
lloyd's on the right track in trying to determine if it's bacterial or a parasite. If you've had these fish for awhile and you haven't added anything new to the tank then its more likely bacterial since most parasites need to be introduced to the tank. Bacterias are for the most part present in the tank all the time and only become a problem when the fish comes under some kind of stress.
Please post back with more information and in the meantime try to fit in a few partial water changes.
Robin