I can't believe the horrendous treatment you have received.
By now I would have thought there would have been a smidgeon of recovery so I hate to say it, is there something else wrong which was missed?
I would return to your surgery and ask why the scan was refused. State you can't afford a private scan and see what he says,
Secondly, you could ask to see another GP at the surgery. Do you know of any who may be more sympathetic?
Thirdly, but this is a very last resort. Go to A&E , ham it up, saying the pain you are in now is worse, and you don't know how it happened. Maybe turning over during sleep? They are duty bound to for some tests and not show you the door. If the treatment is unsatisfactory, ask to see who is in charge.
I know this is a bit hard core and many may disagree, but you have your life to live, now, not in 4 years time when waiting lists are fewer.