There is a large bump that appears on left arm when it is flexed. It is very painful. There is no tingling or numbness. When my fingers are pulled it is the two middle fingers that I can feel it. When I push on the bump, it is almost crunchy like. MRI shows no tumor and ultrasound shows nothing. The MRI did show that around the fatty outside part (towards skin) that there was something there. Just not a liquid tumor. What else could it be?