Hard and solid lump under my right nipple. is this breast cancer?

Could be: Any lump of breast in adult breast including male ( 1% of breast cancers are in men ) should be considered as malignant lesion unless proved other wise, you must see your family doctor doctor, if needed will refer to a specialist.

Could be. see MD now: Absolutely, it is possible to be a cancer. Need to see your doctor. You doctor can examine the lump-and further tests would need to be done accordingly that would include- mammogram/sonogram and biopsy of the lump. Please see your doctor immediately.

Needs investigation: Any lump in the breast needs to be investigated asap. Results for early breast cancer are generally good. See your doctor asap.