So I've found a lump at the back of my neck, slightly left to my spine, and around the hairline. It's firm, painless and doesn't seem to move around. Also it protrudes when I bend my head forwards, but seems to go in with the ligament when I move my head backwards or simply sitting upright.
About two months ago I noticed a similar lump on the back of my knee, which is also quite firm, doesn't move except it goes in and out with the ligament when I extend my legs, although it was painful in the beginning. I went to the doctor, who thought it was a dermafibroma. It went away in about a week.
As we all know, scared... lots of prodding, and I don't even seem to remember whether the lump was always there or it's just appeared! Because my neck was feeling stiff today, so I bent my head forward, that's when I found it.
I'm going to keep it under review and try to see a doctor in a few days. In the meanwhile, if anyone has had this before, please do share.