Blue Green Chromis Weird Lump?

[Deadna]

So I turned on my tank lights today, and my Chromis had a mysterious large lump on his underside. Now, my tank is a 55 gallon, with 2 clowns, 1 purple firefish, 1 chromis, and 1 dragon goby. The parameters are fine. Anyone have any ideas what this could be?
NOTE: The lump is just below his jaw line, and above his pelvic fins.

 

[SpaceFish42]

It looks like it may be a parasite, but I'm not sure...