Something is wrong with my Gem Tang ($3.5K fish)

I'm hesitant to post this, but I could use some opinions. I'm usually the one giving out fish health advice, but when it comes to my own pets, I panic and my brain empties. Gem has been acting strange for a little over a week, and I'm worried about him. This fish is my most prized possession; I really really love him. I got lucky and won him in a raffle from TSM Corals at Reefapalooza NY last summer. These fish typically sell for about $3,500 retail (you can get them for less from places like TSM Corals), so I never dreamed in a million years I would have a holy grail fish like this. I really need to figure out what to do to help him. Check out the video , and if you have any tips, let me know. Am I overreacting? Is he just a little stressed? Or do you think it really could be a mild parasitic infection? Dr. G's medicated reef safe food: http://www.drgsmarineaquaculture.com/anti-parasitic-caviar-detail.cfm More about TSM Corals: https://reefs.com/2018/08/17/lfs-spotlight-tsm-corals-westville-nj/ Reefapalooza NY 2018: https://www.reef2rainforest.com/2018/07/03/reef-a-palooza-ny-2018/