Have a pain underneath my left breast where my under wire sits pain comes and goes feel it more so if i take a breath?

Costochondritis: Costochondritis, or Tietze's disease results from irritation of the cartilage that joins the upper ribs to the breastbone. Pain is typically manifest with movement, deep breath, cough. It is a benign condition, which can be properly treated with nonsteroidal anti-inflammatory drugs, and osteopathic manipulative medicine. Mechanical irritation due to bra wires can exacerbate the symptoms.

See physician: Chest pain under the breast can have many causes including breast cysts, musculoskeletal causes, cardiac and pulmonary (heart & lung), as well as gastrointestinal. If pain when you take a deep breath while not wearing an underwire, that may be pleurisy, inflammation of the outer lining of the lung. If it happens only with the underwire, check without. Please see your physician. If severe to ER.

Muscle vs. Pleuritic: This pain is most likely related to muscle strain from underneath the wire, however pain in this area may also be related to the heart or left lung. Pleuritic chest pain, or pleurisy, involves inflammation of the lining of the lungs and can often present itself as sharp pain when you take a breath as the swollen lung lining causes friction. Proper history & exam is necessary to identify the cause

Seems musculoskeleta: The localisation of your pain seems musculoskeltal and/or pleuritic as it possibly worsens with a deep breath. Try taking an analgesic - Motrin, Advil, (ibuprofen) etc. to see if it goes away. If it persists, and/or is accompanied by fever, then see your internist to make sure its not "walking pneumonia".