in my left armpit,when i raise my arm..just a little below it..not really around my breast...but a little near it,there's a toy pellet gun type of bullet type of lump.. earlier this week, i was having mild pulse like pain in my left breast,sometimes in the right breast.. this would last for 1-3 minutes..then again maybe 6-8 hours,again same pain.. this morning, i was having discomfort in my left armpit itself.. a mild pain.. i noticed this lump few years ago,but back then, i havent expererienced this discomfort..just earlier this week.. what could this be? please help.. thank you