I am 28 yrs old female,weighing 78kg with a height of 5 1. I all of sudden notice an internal lump under my armpit, it is very painful. The pain extends till my chest and my fingers sometimes.I recently stopped breast feeding. and i noticed this lump on the 6th day of my periods(thou my periods were stop by that time).It swallon up the next day but it is of same size since past three days.what should i do?