Women pass through series of many changes throughout the menstrual cycle due to hormonal changes. Breast tenderness 7-10 day before or before start of the periods is due to high levels of hormones. This breast tenderness is associated with many other symptoms. Some ladies also feel breast tenderness at mid of the cycle. This can be due to ovulation. Some ladies also feel pain and can have light periods at this time. So, you should not worry about pain at mid of the cycle.