Mouth rot?

[xREEFINaintEZx]

Hello everyone, got back from vacation this morning and something is wrong with my cardinal. Always keep my water chemistry correct. Going to test everything at lunch. Any ideas from the pic?

 

[reef lover]

Watch him to see if he's ramming the glass at his reflection....

 

[ngoodermuth]

From the photo, I'd say injury. Maybe scraped himself on something. Has it gotten any worse since you first noticed it?

 

[xREEFINaintEZx]

Before I left I left for 7 days I noticed nothing out of the ordinary. The tank has had no new specie's or changes to it in over a year with minimal fluctuation in water parameters. I still haven't been able to test, I just filled a reactor full of carbon and going to do WC in the am.it's been a busy day. Thank you guys I appreciate it.