On 7/10/06 started root canal, was told to call back in two weeks to finish, went back on 7/26 was still having pain and was put on Cephalexin 500mg and told to come back on 8/03 to finish root canal. Went back on 8/03, still had pain in tooth, dentist finished root canal and gave me another prescription for another 10 days of Cephalexin 500mg. Today is the 10th day of taking the antibiotic, (still have another 10 days to go)however, this is the second day after finishing the root canal, and the tooth is WORSE than it was 2 days ago. As soon as the numbness went away after leaving the dentist office, I was in severe pain, the dentist gave me Loratab to take for pain. The tooth hurts when I put my teeth together, the pain is WORSE than it was when I originally went in July. This tooth is on the top, have 2 molars behind it. (This tooth was originally filled in April 2006, after that filling the tooth was sensitive to pressure, thats when I made app. in July to have the tooth looked at.) The dentist said that this tooth should only have 1 root, he has taken 3 different xrays to make sure there isn't another root, he still can only see 1 root. I realize the infection is getting worse and the antibiotic is not helping, what is your advise and what is the next procedure?