I worm when they first get to me. After that, I let them be. Worming them with any water soluble med that works knocks the seven bells out of them, and that can lead to more complex issues. Let them be, and if they are on a good diet with the correct conditions, they won't suffer any issues after the initial worming
I'm surprised the Kisuri med worked TBH. I've tried it a number of times and it's failed each time. When people in emergencies try it, they usually find it does not work also...
Fish are normally carrying all sorts of pathogens, but they only really take over the fish and make them sick when they get stressed (from bad water, tank mates, tank size, transportation, etc.) IMO Discus tend to bicker quite often, and due to there some what more delicate nature I find worming to be a good thing just in case any of these worms take over.