There are many folks here that might be willing to offer advice, but a little more detail is needed. For example, does this spot look like a mole or a birthmark? Does it itch? Has it recently developed or is it changing? Do any of the following apply:

A - asymetrical in shape?

B - border appears jagged?

C - color is black, very dark brown, with perhaps white or blue in the center?

D - dimension is roughly the size of a pencil eraser or bigger?

E - elevated, as in a slight bump?