Well, this I am not sure about. There is a chance that this nipple and not the other one has some discharge happening which is usually hormonal in nature and no big deal. Do you do self breast exams? Lay on your bed with one arm in air, use other hand to feel around your breast looking for lumps or changes, then do the other side. But overall, I don't think I'd be too concerned. Can you mention it to your mom? And next time you have a well check doctor's visit, tell the doctor. good luck
Hm, you have a greasy nipple. Is it just one nipple? Is this a new problem?