That fish eats better than me. Never heard of Kasuri Wormer, but looking at it online it seems the only active ingredient is indeed flubendazole which I can get easily. I have some left over Levamisole from years ago which I believe does the same thing as Flubendazole. I don't really see any symptoms of worms with this fish as the poop is normal. I will keep that in mind should this fish continue to have issues, though.Can you get where you are from Kusuri Wormer plus? It can be ordered from the UK.
It's a flUbendazole based antiparasitic treatment. It's very broad spectrum(for internal and external parasites), a one off treatment or a second dose if a persistent infection. It's pretty safe with any fish but kills snails and possibly shrimp.
I'd try that. Also, look into the diet as well.
The current tank is free of parasites because it's been taken down and decontaminated with calcium hypochlorite. I did use a sponge and media from an existing tank to start it up. That tank had no previous issues. I suppose I'm not 100% sure that there weren't any parasites in the sponge, but it's doubtful.