hi, u forget to mention age of ur wife, which is important in this case. pain in her breast needs further clarification i.e. if it is cyclic or constant/ at a point or generalized in breast/ is there associated tenderness...... so many questions to know before giving opinion.
any way there can be axillary lymphadenopathy
with size less than 1 cm in normal persons also, but it does't give rise to pain, and only sonography
can't diagnose a case as infection or TB or cancer.
I think from the information u gave that it is a mastalgia [pain in breast] d/t fibrocystic disease
in breast. in absence of fever/ infection, antibiotics may be avoided. my advise is to get her checked by a breast specialist, rule out some bony pathology and get treatment for same .