I need some advice here. The inner part of my LO's bellybutton is black. It has been like that since the cord fell off but we didn't dare to clean it too hard. I have been trying to use the alcohol swap to clean it but it doesn't really come off. Do any of you experience this and how do you clean it? The clinic that I send my LO for vaccination says can use olive oil but I am not very sure about it.