I have bad toothache but my dentist can't find the problem. Help it's driving me nuts.?

I have been to my dentist, and he has taken x-rays and can find nothing wrong with my teeth. I cannot identify which tooth it is, sometimes I'm convinced it's at the top, sometimes the bottom jaw. The dentist has started to do a root filling, so I thoought the pain would go, but no, it's back with a vengence. I'm taking pain killers, ibruprofen, swilling with whiskey, even tried vanilla essence. Now have tried dihydrocodeine. Help.