How To Treat A Large Swelling At The Base Of Skull Caused After An Injury?

I fell a week ago backwards on my grandchilds toy, at the base the back of my scull was large and swollen. about the size of my palm. I havent felt well scene. My neck feels a little out of sorts. But I can snap it in place, I havent been feeling up to par. and I have been having some headpain, the not on the back of my head is the size of a quarter, it happened last tuesday, any advise.