<s>[INST] I have pain in the underarm area that is radiating down towards my breast, The symptoms started about three months ago only during my cycle. The second month it lasted longer than my cycle. The third month it is still present 2 weeks after my period. I have some swelling but no rash, cuts, or injury to the area. I have already tried changing bras. Just prior to this starting I had a mammogram and an ultrasound that included the underarm area. My greatest concern is cancer. I have an appointment with my doctor tomorrow to be sure its nothing serious but do not want to brush it off. I have read several articles and my symptoms match some of the time depending on which article I read. Very worried. [/INST] It is understandable to be anxious about unusual pain in the body, especially associated with the breast.  A very common process in the breast that can cause pain & seems to be affected by menstrual cycle/hormonal fluctuations is a benign entity called fibrotic change.  Also, another benign lesion called a fibroadenoma can be responsive to hormonal cycles.  Of course, the only way to definitively diagnose your symptoms includes a physical exam with your doctor, which you are scheduled for. </s>