Bump on head - not sure of origin

When I was waaay younger (as in, third grade) I developed a set of bumps on my scalp which I never told anyone about. I pulled my hair out and picked at them, trying to get them away, and (though I don't know if my obsession had anything to do with this) eventually they did.

Sometime in mid-2007, I noticed that I once again had a bump on my head. It's solid, as far as I can tell, but it hasn't grown at all. I haven't the slightest idea what it is. Could I get some help here?

[Dr_Aparna]

Hi,
IT COULD BE ASEBACEOUS CYST WHICH IS QUITE COMMON IN THE SCALP.
A sebaceous cyst  is a closed sac or cyst below the surface of the skin that has a lining that resembles the uppermost part  of a hair follicle and fills with a fatty white, semi-solid material called sebum. Sebum is produced by sebaceous glands of the epidermis.
The scalp, ears, back, face, and upper arm, are common sites for sebaceous cysts.They are more common in hairier areas, where in cases of long duration they could result in hair loss on the skin surface immediately above the cyst. They are smooth to the touch, vary in size, and are generally round in shape.
Sebaceous cysts generally do not require medical treatment. However, if they continue to grow, they may become unsightly, painful, infected, or all of the above.
Surgical excision of a sebaceous cyst is a simple procedure to completely remove the sac and its contents.
ref:http://en.wikipedia.org/wiki/Sebaceous_cyst
Please visit a dermatologist and get it confirmed.