Hi I have a golf ball sized lump in the back of my arm. It is about 1 inch from the axilla along the bottom of the tricep. It can be felt when squeezing through the little back of arm fat that I have. I have had it for 3 or 4 years and it is unchanged in size. It is firm, uniform, mobile and painful to palpation. I also have breast augmentation from 5 years ago with axillary approach. Thoughts?