Spots In The Breast Near The Rib Cage I Am A 21-year Old, Healthy Female. Yesterday, I Awoke With A Red Sore Spot On My Breast, Near My Nipple.?

I am a 21-year old, healthy female. Yesterday, I awoke with a red sore spot on my breast, near my nipple.? - spots in the breast near the rib cage

It is sensitive to touch, as large as one quarter and slightly warm. I thought I was with my friend's shirt on the bed, perhaps a key, which had dug myself. But it still hurts today. I have no other symptoms and I am afraid to look at sites in inflammatory breast cancer. I have received in school and not very easy to get medical help immediately, so that if anyone has any knowledge in this area would help greatly appreciated. I do not believe that something bad because literally developed overnight (which is not a node, and I) regularly check for lumps that might be wrong.