My 5 Year Old Was Sitting On The Bottom Of

My 5 year old was sitting on the bottom of a hand rail of a stone step and fell backwards. His head hit really hard, several of us heard the thud. He didn't cut his head open but I can see a few spots of blood - like road rash. HE screamed for 10 minutes but then calmed down. He has a huge bump in the center of the back of his head. He said he feels ok but if you touch it he screams and he won't lay back on it. Should he be seen?