If I squeeze it, the pea-sized lump turns white. There is a tiny black dot
in the center
of the
lump, most noticeable when I squeeze the
lump and it turns white.
While I can't be certain of any causal relationship, the development of the lump started almost immediately after a particularly extended period of barbell squats in the gym. I got tired and rested the bar (inappropriately) on my neck instead of the top of the traps. It was painful at the time, but easier, so I persisted.