Help - Petenia splendida mouth

[fishman76092]

I came home from a trip to my 12" snook's mouth very swollen and infected a bit over a week ago. I've been treating with sulfa and melaleuca for 7 days and it's come down dramatically - however it's still not right and what's left looks very odd. He still eats fine and acts normally, but this is the second time this has happened. First time was about a year ago when he was 3-4" and I treated the tank, it went away completely. Now that he's very large the knot under his 'lip' looks pretty solid - but I've not pulled him out to see how solid.

Water parameters - pH 7.8, everything else is nil. He's the dominant fish in the tank with nothing but other fairly mellow big fish - no jaw locking, etc. He does bang on the side glass (unprovoked) most nights, and will only eat sinking pellets...only once they hit the sand. He grew up with the RH Tap Geos and he seemed to be an honorary Geo from then on.

I know how fragile these guys' jaws are and I'm thinking he hurt himself banging the glass or got some sand stuck while eating, which caused the infection. Thinking about pulling him out, pulling his jaws out to check to see if anything is in there (carefully of course) but really not looking forward to it unless absolutely necessary.

Has anyone seen anything like this? I've been keeping fish like these for 30+ years and have never seen it with any of my fish with protractible jaws.

Any help is appreciated.

(sorry for the sideways pictures - they were right side up on my mac)