A little over a month ago, I noticed a hard very small (pea sized) bump under my skin, on the back of my neck very close to my spine on the left side, halfway up. I don't think it has changed in size, but since then I've found two more bumps, another on my right temple (pea sized or smaller), and then most recently the biggest (bigger than a pea but not twice the size) lower on the back of my neck, almost at the shoulder, on the right side, farther from the spine. I am sure the last was not there before... I think I would have noticed after I discovered the first. Since I originally discovered them they remain the same. They seem to be fixed (but my skin is very tight over those areas too), all are the same density (hard, like bone, but perhaps slightly rubbery). What do you think the probability is that this could be cancer? How serious should I take finding these? What do you think it could be? And, how soon should I think about getting this checked by a doctor?