I had a crown put on at end of Dec. 2010. My tooth kept throbbing and then the dentist took an ex-ray. He saw a dead root and abcess. I started taking penicillin VK 500MG 28 tab one tab 4 times per day. I take last two tabs tomorrow, and the next day, Friday,I am scheduled for root canal. My tooth is still throbbing. Does that mean the infection is still with me? My question is should I have root canal done or take more antibiotics until throbbing ( infection) is gone.