High filling in root canal tooth that hurt. After dentist fixed my bite im in more pain now when I bite & dentist says he dont know why? Any help???

Re-evaluation. There are many issues that can be causing your pain, including a fracture, an infection that has not cleared up, an additional canal, etc, etc. Without being able to see the tooth, a radiograph, or knowing the history of your treatment it is hard to give you a proper answer. If your dentist cannot determine the cause, he can refer you to an endodontist for a second opinion.
Unresolved pain. Sound's like it's time for a second opinion. Sometimes because of complexity of the root canal area, recurrent infection, occlusal trauma, and/or fracture, additional treatment is required. Endodontists, root canal specialists, have training and experience beyond the skill set of the Generalist. They also have specialized equipment not found in a Generalist's office. Ask your Dentist for referral.