Although I like Seachem medications, and it’s nice to have them on hand, I’d wait to treat
(while it’s impossible to say anything 100% based upon internet photos, I’d not consider this likely to be any Columnaris variant - medications are stressful to fish to varying degrees so I don’t medicate unless I observe something that is likely to respond to medications)
Not to mention that Columnaris is very difficult to treat with medications (despite any hobby market claims to the contrary), even when the Columnaris variant has been identified, and medications tested in vitro in order to choose the most effective, in vivo treatment of infected fish, yields at best a reduced mortality rate ...
You could prepare some medicated food, if you want to be conservative - Seachem has some directions on their website (and more on their Discussion Board if it’s back up), you can also email them photos and tank etc details, and ask which of their medications they might suggest (if you do this, it would be nice to report back here
)
Seachem Focus is definitely worth buying, it’s used to bind medication active ingredient to the food (there are various scientific studies supporting the use/efficacy of these binding agents)
When feeding medicated foods, I use Hikari Frozen brine shrimp, blood worms as the food base (as my fish love these), flake food usually breaks down too much, small pellet foods can be good
(I rarely feed freezedried bloodworm or brine shrimp as they seem very resistant to “wetting” in the medicated solution ... and my fish are not keen on these at all)