I hit my head please help me!?!?!?

Yesterday I was leaning on my door and hit the back of my head on the doorknob. It hurt right after and then turned into a headache. I've never really had a head ache like this before. My head feels like it's ringing and it aches badly. I went to sleep and when I woke up this morning it kinda felt better, but know it's really bothering me! What do you think is wrong? Is this normal? I'm scared