lump under left arm and on neck

I have had a lump under my left arm and on the left side of my neck for over a year. I had a mammogram that showed 3 enlarged lymph nodes, they said it was normal. Recently I feel pressure under my arm (like I'm holding something) I have been referred to have the lumps biopsied. When I went to the surgeon he dismissed the one under my arm and is sending me to have an ultra sound of my neck. I don't want to be paranoid , but I am concerned about the lump under my arm because I have never felt this pressure before.