Hard like cord up under breast, hurt when i stretch out or touch it.

Full breast eval: Any breast symptoms warrant a physical examination by a specialist (not primary care physician) who may recommend imaging or biopsy. Early diagnosis is essential for survival of breast ca. Better a hundred negative evaluations than one missed evaluation in the early stage of true neoplasia.

Could be many things: The description is very non-specific. However, the best answer is to have your primary physician examine you and order appropriate tests as needed. Given your age i would think the process is most likely benign but better to be examined and evaluated.