Is it ok to be having head aches after hitting your head?

Just making sure. It happened a while ago around 4:00pm. i was sledding and i swerved and my sled hit a rock flipping the sled over and my head hitting another rock. (it was my forehead) I wasnt knocked out i got right up after it. I was fine until around 5:30 when i started to get a head ache. Afterwards it went away and came back and it keeps doing this. LIke stay for 5 minutes then go away for like 1-3 minutes. I had a bump but it went away and i have a red mark the size of a nickel. I had no dizzyness. Do you know? Is it just a cuncussion?