Tumor or cyst?

So I have been out for a few days from home and gave the responsibility to my older brother to keep with the tank, and I don’t think it turned out well. I noticed one of my severums has what looks like a cyst. Not sure if it was an open sore that got infected.. I am about to do a large water change, but besides that, would medication be needed?

It could be a small sore.

Do a 75% water change and gravel clean the substrate. Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Add 2 heaped tablespoons of rock salt for every 20 litres of tank water. Keep the salt in there for 2 weeks. If you do a water change while using salt, add salt to the new water before adding it to the tank so the salinity (salt level) remains stable.

If there's no improvement after a week with salt, post more pictures.

Will do!

Could just be a battle mark as sometimes the other severum chases after him.