Jen, it's too soon to say if this could be a sign of breast cancer.  Probably not, because you say it comes and goes, and cancer symptoms tend to come and get worse.  The pain and tenderness I had that turned out to be the initial symptoms of inflammatory breast cancer were intermittent at first, but quickly (within a couple of weeks) became constant.  I had been told that "breast cancer does not hurt", so I had no idea that my symptoms could be cancer. You will notice that when PJ Hamel and I answer questions about breast pain, we are always careful to say that breast cancer USUALLY does not hurt, or pain is not a TYPICAL symptom of breast cancer.  The typical cancerous breast lump does not hurt, especially compared to the breast cysts, which are often tender to the touch.  However, there are many forms of breast cancer, and every person experiences symptoms in her own way, so it is important to have a doctor check out ALL breast changes that last longer than a menstrual cycle. Since you have had this pain for only a couple of days, it is way too early to panic, but it is good that you are paying attention to breast changes and doing some research about what might be causing the problem.  Check with your doctor right away if the pain becomes severe or if you develop other symptoms.