Im 16 year old boy that found painful lump in my nipple when i touch it, i want to know what is it? there is no discharge, could it be cancer?

It's not cancer: About a half of males will undergo a transient nipple/breast enlargement at the onset of puberty. Normally it will resolve slowly as other hormonal changes kick in over about a year. Less often it can persist over 3 years and surgery may be needed for cosmetic improvement. Carrying around extra weight can aggravate the issue as fat can masquerade as breast tissue.