Hi!
I'm glad you came by to check with us and to get some support. As the other two folks that posted said, it doesn't sound like cancer, and you are pretty young for cancer. Not that it hasn't happened, but it is unlikely given your description and your age. Having said that, though, you should go to your dr with this. As a young woman, it's good to get in the habit of being very familiar with your own body, and know when something's changed. The most important part of that, then is the follow up! If anything is bad news, it's better to know it earlier than later.
Best wishes to you, and let us know how it turns out!
Warmly,
Chris
Healingwell62
Breast Cancer Community Leader
If it is between your breast, I am not sure that is breast cancer. No matter what, you need to see doctor. Let's face it.
Given you age, and the fact that you describe it as "long" makes it not sound at all like breast cancer. You need to see your doctor to find out what it is though.