I’m with many of my collegues. By 8 weeks you should be starting to see some reduction in pain. Although the pain may not completely be erased. If you are not, I would follow up with your physical therapist or physician.
It is also important that you are monitored in the way that you are performing the exercises and that you complete any homework your physical therapist may have given you. If you are unsure of how to perform different exercises or how often you should be given the various homework your therapist has given you, then please ask them to clarify. If your therapist did not give you any work to do at home, I would ask them what you should be doing between your sessions to help ease your pain and then to strengthen your weak areas and strengthen your overly tight ones. Usually where there is pain there is an imbalance and over-compensation, so it is important to strengthen and stretch the cooresponding areas.
And as Karin said, if you are not already seeing a physical therapist and/or physician for your pain, please do so. A personal trainer is often ill equiped to diagnose your problem and if there is pain, you should always be seen by a physician to receive treatment, not a personal trainer.