I have a chronic, recurring toothache in one tooth. Possible causes?

Background information: I have had braces twice in my life--once when I was 12, and once when I was 21. Ever since then, I have had a problem with a feeling of pressure and pain in one specific tooth. Long periods of time can go by without my having a toothache and then suddenly it will happen. I am wondering if this could have anything to do with nerve damage or something from having braces twice. I have heard that the pressure of braces on the teeth actually is a kind of trauma and it is better not to have them more than once. Unfortunately for me, having them twice was unavoidable. Thanks.