Open Question: head injury, concussion?, hit my head,?

I hit my head on my way out of the subway train, on the gates rim. This was exactly 3 weeks ago. First, it was just a normal hit on the head, it didn't feel unusual. But I became more and more frightened as the numbness on my head (constant), and a short, reasonably sharp headache (occasional) persisted. I hit my head on the top right roof of the skull, and the numbness is on my bottom back right. Early on, the numbness was on the right. Head aches usually hurt the sides. The ear rings but it has gotten better. What frightens me the most is the sound, similar to the one when a rice crispy is torn apart, that I hear when I rest my head on my pillow, or walk down the stairs. It feels as if not enough blood is going into my brain. and I feel tired. All the while I played soccer, got a flu, and have not gone to the hospital yet, which I suppose was really stupid, because all of these kind of made the situation worse. I have an exam tomorrow, and classes are pretty tight until Saturday. I feel tired when I think. I'm also freaked out about the possibility of losing my thinking ability, as this is really important for me.