Is this shell rot?

[jjjes1386]

I just recently adopted this little guy amd while inspecting him I found this spot on his she'll on his belly side. The shell is jagged around the white spot which feels rough

 

[mike taylor]

Looks like some fungus . I'd wash him with some medical scrub you can find at wal-mart. Then I'd put some betadine . Then get some cheap athletic foot cream and put that on daily until healed . Only put the betadine on once the first day . Then the athletic foot cream daily .