What could this be?

Makenzie

Hey everybody,

So I just noticed my 16 month olds toe. She’s had shoes on all morning due to being out, it was not like that when I put them on her this morning. She is running around & walking perfectly fine & when I press on it or move it she does not wince or act like it hurts at all. Should I worry? Or just watch it? What could cause this? She had on the mesh sneakers.