Hi. I think it is great that you are on top of your health! I, however, would not correlate this to breast cancer. First, you are not the typical demographic that would get breast cancer at 13 years old. That is very young and breast cancer would be incredibly rare at your age. Second, a spot on the breast is much more likely to be skin related rather than breast cancer. Breast cancer presents typically as a lump and frankly, a lot of times women don't even know they have anything going on as symptoms are absent and it is found on a mammogram that is abnormal. Internal imaging shows it rather than seeing or feeling anything on the breast itself from the outside. So, a self breast exam is important. You feel for lumps. I had one once and it was a fluid filled cyst. No big deal so don't panic if you ever feel anything. You tell our mom and then just get it checked out. But back to your red mark on your breast. So, sometimes they mention skin changes with breast cancer. It's often something like dimpling of the skin. A red mark could be from something hitting it, a mole, etc. Can you show your mom? She may have some insight on it and can have it looked at if she thinks it is anything suspicious. But I would not be worried about breast cancer at this point sweetie.