Sharp stabbing pain in between breasts, between shoulder blades and front bottom of neck, comes and goes suddenly, hurts to inhale deeply.

Needs further workup: This very well could be pleurisy, which is an inflammation between the chest wall and lung. Having had a recent respiratory tract infection is a classic preceding finding. However, it may also be a sign of a more serious condition, especially in the setting of shortness of breath, swelling of the legs and history of smoking and use of birth control pills. See your doctor for a physical exam ASAP