Hi, I've Had A Dime Sized Bump On My Scalp

Hi,
I've had a dime sized bump on my scalp for about a year. It was painless but I always know it was there. Last week I was in a car accident and got a cut on my head over that bump. After pressing on the side of the cut a white dime sized ball popped out. After cutting it open some clear liquid came out. The inside walls of it are not smooth. What could this be? Should I be concerned?