Dude, seriously, you don't need the infirmary. Your plant looks awesome, just looks like something damaged the leaf a bit. How many are like that? If it's just up to 3, I'd pluck them, be very careful that:
1) nothing gets splashed when I water/feed the plant, and
2) the leaves aren't touching anything, like the wall, etc.
And keep an eye. Now that the damaged leaves are gone, it'll be easy to monitor. If the problem is gone, no new bad leaves. If it persists, then let's find the problem.
Sent from my SM-N920T using Tapatalk