What Does Knots On The Arm Indicate?

I have three knots on my arm. They are soft and only visible when I move my arm in a flex position. I asked a doctor today while in the ER for chest pain, and he said it could be over 100 different things, vut nothing to do with my chest pain. My arm will start to hurt and i feel pressure whenever i lay it down on a table. i noticed these knots about 4 days ago, and have never had anything like them before. i have not done any form of heavy lifting recently.