Baby chick with a bump on her bottom?

[Amsignorelli]

I have a black silkie (I believe seven days old) who seems perfectly healthy and acts just like the other 3 I have. Eats and drinks, may be the smallest chick though seems to have a small bump on her bottom ( I thou was pasty butt) so I clean. It is not pasty butt but a small bump on her bottom. Should I do any thing or just leave it alone? What could it be? Thank you in advance.

 

[Northwest_Wannabe]

Could you try to take a photo? : )

 

[Amsignorelli]

It actually looks like I got a little bit bigger and the first time I saw it there definitely was no discoloration, I did just clean her off because her poop keeps getting stuck to it. I’m just curious as to what it is and the likelihood that she Will survive also if there’s anything I can actually do for her