My left breast is sore to touch, its been that way for a month?

Need more info: Male or female? Gynecomastia can be a tender breast swelling in males, usually resolves with time, and would be best to see a doctor for an examination. Breast tenderness in women not uncommon from fibrocystic conditions, and can become worse during the menstrual cycle.

Other symptoms?: If there is no mass, no fever, no lump, no change in skin, you may watch and wait.