What is this?

A few weeks back I felt something weird along the side of my right breast.  It was about the size of a dime and honestly I wasn't really concerned but after a few weeks I thought it might be a good idea to just have my doctor check it out since I could still feel it. 

My doctor could feel the little lump too so he ordered a mammogram and ultrasound just to have things checked out.  Truth be told I was 42 and had not had a mammogram yet anyway so it was time to jump on that band wagon anyway,  The center offered me an appointment for the 8th (just 4 days later) however I had a conflict that day and opted for an appointment on the 15th.  I wasn't concerned or worrying and figured it was probably just caffeine related or something.