Slight pain in waves on down left side of chest near armpit from a week.

Pains: Pains in that area, if Sharp,shooting,fleeting,aggravated by a deep breath could be a pinched intercostal nerve or muscle irritability. Other possibilities include rib cage strain if the area is tender. Any history of injury? Lung pathology is unlikely without an associated cough. If symptoms persist see your physician for evaluation. An xray may be recommended.