Do i have concussion?

basically, me and my friends made an indoor skate park; i was going full speed towards one of the ramps, when one of my friends shut a massive door onto me by accident, made out of metal. It took me clean off my board and i have a bump on my head and it bled a tiny tiny bit. I didn'tt have a headache but it did hurt for about 4 hours after. Its the day after and i feel a little bit slow etc. i dont know whether i have it or not, please help!