Large white spot on side of Silver Dollar Fish

[KnoxicWaste]

My silver dollar fish has a large white mark on its side. I am unsure what this is and have struggled to find what this is online. It does not appear to protrude or sink in; seems pretty flat. I'm worried this will spread to my others as well. Does anyone know what this is and have advice? I do not have a hospital tank at this time and do not know if it would be worth stressing the fish further (and the others) by chasing it around the tank, destroying the nice ecosystem. The thumbnails look like they are upside down, I am not sure if they will flip right side during the posting process or not. Thank you all in advance for any help.

[Colu]

Looking at the pictures it could be a bacterial infection with possible secondary fungal infections what I would do is a course of jungal fungus clear fizz tabs containing nitrofurazone @KnoxicWaste

[KnoxicWaste]

Colu,

Thank you for such a quick response; meds are ordered and we'll see how this goes.

[KnoxicWaste]

Update:

The meds you recommended should show up soon, however, I wanted to share where we're at in case this helps in the future. I believe I have an outbreak of blue-green algae (cyanobacteria) in one of my tanks (I can smell it), so I treated my two main tanks with Blue Green Slime - Ultralife Stain Remover. When looking at the Silver Dollar Fish last night, I kept counting them as I couldn't find the infected one; eventually realized it's healed up very nicely. I'm not sure what that means as far as what the fish was suffering from, but it appears to be doing great now. I'll just keep these meds in my hip pocket for if this problem returns. Thank you again for the help!