Hey I a lump on the back of my head. I've have had it for years and usually only hurts if I mess with it. I was looking on the internet and saw that it could be an external occipital protuberance or a bulging of the occiput. does anyone know if that is different? But I mean it doesn't really bother me too much just wondering if anyone knew what it could be. I would say it's smaller than golf ball but a lot larger than a marble.