Hello Aimee
It would be impossible for anyone on the Internet to tell you what is causing your pain. My suggestion is to not let this go on anymore and get it checked out by your doctor. Do you have any other symptoms? Has the skin texture changed? Have you had any injury to this area?
I am going to give you the link to our breast cancer site. They may know more about this particular symptom there.
Please do schedule an appointment with your doctor now.
Thank you for your question.
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