Is a lump after a bump something to worry about?

I had a nasty fall and landed on my cheekbone on my car. I have managed to get rid of the bruising (which was bad) and swelling with 9 days of constant Arnica. But there is still a hard lump under the skin which is quite painful to touch. Its not really noticeable but when i touch it or blink hard it hurts? Is it anything to worry about or will it just go away?