What Causes A Lump On The Cheek Bone?

Hi,
I have a lump on my cheek bone (about 1/2" below my eye), the skin is pink coloured on top. Feeling it now, it seems to be a ball with a little V on one side. Originally I thought I might have bumped it in my sleep, but it has been 3 weeks now and hasn't gone down in size. It was tender when I first noticed it, but it's not nearly as tender. It's not a pimple - I've had them be hard for a day or two but not like this!

Thanks!
Anissa :)