I suspect this wrasse is suffering from this new disease / syndrome. It just came out of QT into a holding a system while I finish a new build. It’s still having a feedings response but is becoming increasingly uncoordinated in its swimming. Too bad, I love the Fairy Wrasses, but I won’t be buying any more until this new issues is identified & hopefully with a treatment.
Could be, it has the key symptom of still trying to feed. However, this fish seems to have a white spot on its head, that *could* be a symptom of having jumped and run into something, which is the often given cause of this syndrome. However, you say the fish is getting worse - injuries don't do that, they are acute and tend to get better over time, not worse.
Jay