Lockjaw in yellow tang????

[Cujo#31]

All my perams are spot on, I have not introduced any livestock to tank in months. Have not lost anything in months. All fish are currently in 120 hospital tank awaiting transfer to new tank. Last month I ran all fish thru ich/anti bacterial treatment before I put everything into new tank as precaution. I left the fish in the care of mother-in-law while we were away for 4 days. I got home, did water change, and had to head out again for a few days.Each days feeding was placed in zip lock bags labeled for each day to avoid over/under feeding. I have to head back out for a few days and I'm a little worried. All the other fish are eating well and none show signs of any stress, anxiety, or health issues.
My usual pig Yellow Tang looks like he has lockjaw. Swims right past food. I'm just a little concerned. Appears to be breathing a bit faster than normal.
I feed all fish a mix. Mysis and Brine shrimp, blood worm, sinking pellet, and purple seaweed. Anyone have any ideas????? Can't download pics to save my life. I could email pic to someone if they could upload for me, but no imagination needed for yellow tang with jaw locked open