Hi,
Many conditions do cause pain in the axilla (armpit) region which can be due to lymph nodes, breast tissue and so on.The basis is of any pathology is an underlying inflammation. It is advisable that you schedule an appointment with your physician for a proper clinical evaluation.
Hi. There are so many things which can cause underarm pain. It is really better to consult with a doctor to have it properly assessed and treated. Offhand, axillary pain can be due to a musculoskeletal problem (example: arthritis, trauma, sprains or strains, muscle cramps). It can also signify an ongoing infection or inflammation (cellulitis or abscess in the area).
Forgot to mention, I am 27 years old, haven't had any related problems.