You need to try to clean them as good as possible. I would start to bath her feet in water with epsom salt. With so many lesions it's only a matter of time until you have bumblefeet at your hand. and it probably already started, ( I've added a picture in my earlier message)
The oystershells are...
Never seen this! it runs up the leg too?
What kind of surface do they walk on?
Are those spots like discolouration or lesions in the skin?
curious wat others think!
This might be bumblefoot but I can't tell for sure with all the spots everywhere...
[edit: I see you describe them as small...