Probably just a cyst. They commonly can stay for a long time, and then resolve on their own. If not, see a doctor and have it checked out.
a penis
Sebaceous Cyst.
It is probably just a pump knot she could get this by hitting it or repeatedly rubbing it. But I would see a doctor to make sure.
It depends on how hard or soft you have hitted your head
You have a goose egg. It happens when you smack your head on something really hard.
A bump is not bad. It is just an area of swelling. If it was a hard blow or you passed out at all.
mastoiditis
You should go and see a qualified medical practitioner (a doctor) with this problem as soon as possible.
Bumping of the head could mean your cat isn't seeing right or could be a sign of illness, I would get a vet to look at him/her
You should probably see a doctor. That sounds like a pretty hard hit.
It is hard to make a diagnosis but it could be anything from a white head to a fatty bump. If you are concerned see the doctor.
No butter does not cure a bump on the head, but try spreading it on your toast it tastes great.