I have noticed a developing dent, changing size, in the back of my skull. This started 3-4 months ago, no trauma caused this. I am also worried about 4 (3 occipital, 1 in front of ear) hard yet small and mobile lymph nodes that have been swollen for about 2 years. The only illness in my immediate family is diabetes and ceiliac disease. (i have neither) I was just wondering if this could be caused by cancers or a tumor. The dent changes size from deep to shallow, and slim to wide. Any possible explanations will be GREATLY appreciated, thanks!