Not sure if this is a cavity issue or not...I dont think that it is

everytime I walk I get a shooting pain in my tooth, that is - every time I take a step with my right foot anyways. Somehow its directly related to this pain in my tooth. This used to happen before, every once in a while, and then it goes away. The reason I dont think this is a cavity is because I used to get this pain, and I went to the dentist afterwards and they did not find any cavities. Now that the pain is back im not sure what is causing it, but I need to do something about it because it hurts :s!