Watchman goby woes

[Dash]

I have a bit of drama in my tank, not sure if anyone has experienced something similar. So my YWG, Snape, lost his shrimp buddy recently. They were my first livestock purchase more than 4 years ago and have been an awesome part of my tank, always front and centre, opening shop every morning. Anyway, Snape has been showing signs of stress since his loss. He has had white patches & streaks on his body. He has abandoned his old burrow, where he always used to chill in the doorway, and swims aimlessly in the open, at times frantically. He acts like he’s lost.. He’s not interested in eating. I phoned every LFS & of course no pistol shrimps anywhere.
It’s been a week or so and I’m getting worried. I’ve gone thru a lot with this guy & he means a lot to me.
Any ideas?