I have periodic tooth pain?

I had a filling four days ago, and last night my tooth randomly started hurting really bad for about half an hour, then suddenly stopped. I was able to eat dinner and everything. this morning, I got up and felt fine, and started having a shower. As I was showering, the same pain came back and it has been periodic for the last 3 hours. I have an exam this afternoon. I need help asap. What can I do?