Yes, a tooth may hurt after treatment. Not unusual for a few short days that a little ibuprofen or acetaminophen can't handle. More than that, then a trip to the dentist to evaluate it. It often is the bite being too high. Simple enough for your dentist to adjust. Sometimes food is banging into the gums between the teeth; a deep cleaning in there and restoring should help. It might be another tooth, again, your dentist should check it out. If it is the same tooth that was treated, then perhaps a trip to an endodontist for a second opinion...maybe an extra canal or fracture.