I freaked and saw two docs this week (primary care clinic) for a pea sized lump in front of my ear that I've had as long as I can remember. I had several ear infections a year for the first 50 plus years of my life. Pea sized, symmetrical, moves easily, buckshot.... Both docs told me 'shotty nodes' or scarred from so many infections, etc. In fact, my favorite doc said there's a smaller one in front of that one but deeper and that shotty nodes generally will be all of the nodes in that group sort of clustered together. Nothing to worry about.
About the one in your neck and back of your head. The one in your neck was never pea sized. Those were always bigger even before an infection. On the back of your scalp, my son had seborrhea dermatitis (bad dandruff) as a pre teen. His nodes back of his head were as big as marbles. Derm said they'll go down when condition is cleared up but that we'll always be able to feel those. He said newborns have nodes that are virtually nothing until the first 'use' or infection and then they never return to that 'nothing' size again.
I wish we could all accept what we're told without second guessing. My mother will have heart tests which are perfect, drive out of the doc's parking lot and think, 'Okay, now THAT was a heart attack at that stop sign!'