Could I have skin cancer? The shoulder with the mole on has been really achy and painful. (Photo)

I have a mole on my shoulder. That's been there about 2 years now. It's looks black and really iches. I've had heartburn for five days straight now. I've never suffered heartburn before. So I went hospital 2 days ago and they couldn't find anything wrong with me. The shoulder with the mole on has been really achy and painful.