I Have A Soft Lump Right Below My Elbow On

I have a soft lump right below my elbow on the outside of my arm. My Dr said she thought it was soft tissue swelling. I am concerned about this and wonder what tests should be done, what treatment etc. It does not hurt at all but I think it is getting a little bigger. Would appreciate your opinion. She did an x-ray of my elbow and it was normal.