I have had this big dark brown almost black spot on my big toenail. I tried treating it with tea tree oil for a week and there is no change. I’m scared it could be melanoma? It’s only under a nail and not growing out, nail is a bit yellow but not much, spot takes about 1/4 of a nail and doesn’t really have a shape. I’m a teen and really don’t want to go to my parents so that is why I am asking and also don’t want to go to the doctor if not really necessary.