Gourami has spot on head

I have a few Gouramis in my planted community tank, 75g. I guess it's been
set up for close to 3 months now, it's been pretty stable no deaths in a
while. Last week I added two new fish though, 2 African butterfly fish. It's
probably a little overstocked, 7 gourami, 6 rosy barbs, 3 danios, 4 clown
loaches, 4 cories, 1 red tailed shark. I guess it's about 80 inches of fish.

I had one of my starter danios die. It had it's skin torn open, I don't know
if it was chewed on while alive or after it died though. The red tailed
shark doesn't like the barbs for some reason. he is always chasing them when
he sees them. Clearly the Butterfly fish are carnivores, they are pretty
laid back though just sitting there, I haven't seen them try to gobble
anyone.

My question is whether this spot on my gourami is an injury or some sort of
disease I should medicate. She has a discolored spot on her head that looks
like a torn scale, it's light grey in color. It's generally discolored
around the area as well, dark, but it may just be where she naturally has a
dark spot. She is behaving normally and tries to eat everything that gets
put in the tank just like the other Gouramis. The larger yellow male is the
dominate Gourami, he chases the other Gouramis sometimes as well. So I
suppose there are 4 suspects who may have damaged her, the larger Gourami,
the shark or the 2 butterflies.

http://www.avadb.com/photos/GouramiScale.jpg
http://www.avadb.com/photos/GouramiScale2.jpg

The second photo doesn't really show the lifted up scale but it shows the
color of the grey spot around the damaged scale. My guess is some sort of
fungus, or is it just a bruise or natural coloring, do fish bruise?

Thanks,