The lump could be anything and it needs checking out.
Having read the history of this question, I would strongly urge the question originator to seek Parental advice.
asians
Coccix bone
There could be many reasons why a person would have a lump on the buttocks. The lump could be a cyst, keratoacanthomas, or a neurofibromas. A doctor will need to be consulted to find the exact cause.
Any lump (painless or not) is cause for concern. I would get it checked out, it may be nothing....but it could be something serious, you should get it checked early. It could be something as innocous as harmless skin lump or it could be something more, go to the doctor to be checked out.
For a lump on the back of your head you could see a dermatologist (skin doctor) or oncologist (cancer specialist), or possibly an endocrinologist (if the lump has a hormonal cause). For a lump in the back of your head, you could see a neurologist.A general practitioner / family doctor will be able to give you a "top to toe" check up and see if there's anything you need to be referred for.
It could be an imbedded tick.
You should see a doctor. You could have bleeding within the tissues which can cause the lump. You should see a doctor. You could have bleeding within the tissues which can cause the lump. You should see a doctor. You could have bleeding within the tissues which can cause the lump.
It's in your genes...
sebaceous cyst sebaceous cyst
Yes it can, especially if it is on or near the sciatic nerve.
A smelly lump on the back of the head may be an infected abscess. It could also be a sebaceous cyst.
A lump on the back of the head could be a simple knot from hitting your head on something like a cabinet. It could also be a cyst. A doctor is the only person who can diagnose the lump.