It is very difficult to tell what this lump could be without clinical examination.
You don't state your age,but hormonal changes in teenagers may result in the feeling of a lump under the areolar in one or both breasts (gynecomastia). This can occur in both teenagers and young men too and it's expected to resolve in a few months in the majority of males.
Depending on your age, cancer is highly unlikely, male breast cancer is extremely rare until later middle age at the earliest.
However,a lump may also occur due to endocrine diseases, or the intake of any kind of supplements or medications that may affect your hormone levels.
I would advise you to seek medical consultation to exclude any serious causes.
I am a 23 year old active male. Though slightly overweight.
I have recently been taking suplements in the form of whey protein, fat burners and metabolisers...as i am trying to cut weight and increase muscle for a competative fight. But nothing that i am aware that should affect hormone levels.
Thanks for your help, i am on my way out to see the doctor now.