I can't tell very well there in the pic, other than it looks sore.
Keep the water quality perfect 0 ammonia, 0 nitrite and under 30 Nitrates and Keep doing pwc
very frequently, keeping the water as good as possible. If it looks worse in a day or so then it would mean medicated treatment.
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article
FW Favorites right now Clown Loaches, any shrimp - SW Vase Red Mangroves