I have a lump on the back of my neck?

its a little above the hairline on the right side in the tissue that's between my neck and the bottom of my skull. It's kinda hard and its the size of a pea. You cannot feel it unless you apply pressure and if i move my neck around. Any idea what this can be? I'm 19 so I feel like cancer would be rare and it is definitely not a infected hair follicle it's deep in the tissue.