Please help.

Okay I am in the midst of having a panic attack. I have had this mole in my belly button for a long time and had it checked out by a dermatologist about 2 years ago and he said it was nothing to worry about. I was having a bath earlier and noticed that it has more black in it and I looked at symptoms of melanoma and I am just shaking. Is this mole cancerous? It's in my belly button too. I apologize for the gross photo but I am scared right now :(