Oh I'm so glad you know there's a Pain Clinic nearby! If it's a muscle spasm then relaxant drugs can help, or you can have trigger point injections if those don't work - I have had those and the results were absolutely amazing
Please don't ever feel that you're a nuisance. Chronic pain is miserable and you have every right to have help with it! Hopefully if you get the muscle spasm sorted then you'd be able to get back to your physio exercises again.
Good luck with the Pain Clinic, let us know how you get on