What should I do about my tooth?

I had a broken tooth that became infected. I went to the dentist, who suggested I get a root canal. I had the root canal done about three weeks ago by an endodontist, and afterward, my tooth started hurting even more. I can't put any pressure one it or I get a shooting pain that goes into my gum. I've been taking pain medicine just so I can eat and I've had a round of antibiotics before the root canal, and one after. It still hurts. I got an x-ray last Friday, but didn't get a clear answer. The endodontist said it was just inflammed and it would heal eventually and my dentist said I had resistant bacteria in there and gave me yet another round of antibiotics (3rd round), which isn't working so far. I'm getting frustrated. I'd love to be able to eat without excruciating pain.