Melanoma

Could it be malignant?

At first it looks like a liquid on my arms or hands, then small circles with red insides form and within 1 or 2 days it turns into a mole. I want to know why or how should I proceed?

A black line appeared on the nail. It was short and fixed. It did not change at all. It appeared after a single pressure.

What do you think this is?

Hello, there is a fly on my nail.