Dear Sana
I think you face with chronic pain, in this case you need to change your approach to this patient as it is important to consider the same thing in all patient.Now the pain is accepted as multidimenssional concept,BioPsychoSocial. involve in your team if you work in the hospital Psychologist to assess his Psychology condition, occupational therapist to assess his Social aspect of the pain and Biological aspects you already done.
Regarding to the treatment you applied was fine in my openion the only thing is the pain you have to stop it as soon as possible, because your patient will lose his confidance about your ability to fix his problem.As you mentioned he was treated by PT before but there was no progress and this might affect his believe on the ability.If you can't just send him to pain management programme and they will cover all the aspect of the pain.As rehabilitation I think after hotpack you can do SLR gradually by streching the Hamstrings Muscles with motivation of the patient to relax with deep breath, and try please to know your patient verywell. and see if he still trust on you.Hope this well be helpful otherwise just send him to any pain clinic to assess all the aspects of the apin and its effect.good luck:rollin