Hi, I Have A Long Indent In My Breast, More

Hi, I have a long indent in my breast, more prominent when my arm is raised and feels very hard to touch. It’s quite painful and I’ve since felt a lump that moves a little bit when pushed.. in 31, otherwise healthy. I do work out and discovered the pain and indentation after a new workout of my upper body..
Dr has referred me for an urgent ultrasound but I’m worried as I can’t get in for a few weeks.. could this be breast cancer?