I have

Mkay well..I've had a sort of lump on my left breast for..i don't know how long, maybe 4-6months.
The lump is on the upper-outer part of the left breast, you can't see the lump, there is no discolouration, and it's tender-kinda like a bruise but i read that in thin people or people with smaller breasts it's common to be able to feel small lumps like the ducts and bulbs, but the lump i'm concerned about is a bit bigger and doesn't have a particular shape to it or anything.. umm..it's not itchy at all, sometimes when i run, if im not wearing a sportsbra it hurts on the land but thats pretty rare..
I think the lumps more noticeably tender around my period, i'm due to get mine in a week..so yeah.
I havn't spoken to my GP about it.
I'm sixteen and a C cup if that helps.

[japdip]

Well, you should speak to your Dr. about this. A little advice here ... you should definitely wear a GOOD supportive sports bra when you run. It is true that breast lumps are fairly common that are related to the hormone levels in your body (around the time of your period); like you said. They do occur in your age group also. If you would speak to your Dr. about this I'm sure you might get some valuable information that might help with this condition.    Take care ....