Can anyone tell me if I should be worried about my crown?

[CharlieDay]

The general shape varies. At some moments it'll be fully covered but at some times it can look like this: https://imgur.com/Ed2CfPx. Let me know if this looks familiar to anyone and if I can and should be doing something about it. Is it better to see a general doctor or a dermatologist?

Additional picture: https://imgur.com/XHPno6W