A Pimple on my ?

I don't exactly remember when i got it i would guess about two weeks ago. Anyways it looked like I had a little pimple on my around the nipple area. I thought i would just let it be and it would go away. But about a week ago it started kind of peeling away at the edges of it, and slowly kind of grew a scab (a greenish red color). But last night the scab sort of lifted up a little and I could see what looked like a little crater beneath the scab. That's when I really got worried. Can anyone help I can't help but wonder if it has anything to do with Cancer. Also I am only 14 years old almost 15. Please help me out, Thank you.