I'd be interested in the back label on that bottle. I'm suspecting tea tree oil...if they confess what's in it.
A google search turned up the completely silly statement that it 'contains no chemicals,' which is impossible: everything in the universe is chemicals, including natural substances. The question is, which chemicals does it contain? It may simply increase slime coat, which would help the fish with either ich OR lympho, so we're still stuck with not knowing what we're dealing with here...
A lot of fish-vet stuff is like that: you treat for symptoms and try to alleviate symptoms. IF it turns out to be lympho, it will be nice if it can treat the symptoms, and even nicer if it doesn't adversely affect the tank (tea tree oil is pretty benign) and make the problem worse. And, being lympho, it will go away quietly and the med will have a little credit for at least making the fish more comfy.
The one thing that gives me a bad and creepy vibe about this stuff is that they claim its for 'ich', which is not a disease, but an animal, a parasite, that I'd rather kill than cure, thank you. Nothing we know of is going to kill ich without killing off your bacteria, and it says it won't do that.
If it is ich, a miracle-in-a-bottle is not going to stop the parasite from coming back. But.....let's hope it's going to help the fish feel better, eat, develop slime coat and stand a better chance of surviving another assault by a parasite---or just generally get better if it's lympho. The med is interesting stuff, and I'm sincerely extremely glad the fish is doing better. If you get information on the contents or composition of that med, I'd sure like to post it. They're not admitting anything on the internet, so that says to me it's a known ingredient, and it may not confess it on the back label, either.