I can empathise with your situation completely, as my similar condition went undiagnosed by the NHS for 3 years!
Everyone who posted to you on this site mean well, but without a full, unbiased, clear and independantly reviewed MRI Scans & X-rays you are just taking you GP's & Consultants 'best guestimates' as gospal
I saw 3 GP's, 3 Pysiotherapists, 2 Radiologists, 3 House Doctors and 2 Consultant Orthopeadic Surgeons and all of them missed my 'very common' condition, a condition that sounds very similar to yours!
I had an arthritic condition called (Osteophyte overgrowth of my facet joint). This bony overgrowth (bone spur) was on the underside of my L5 facet joint and when I stood upright or extended backwards it squoshed my sciatic nerve root at the foraminal opening as it left my spinal canal. This was completley missed by most & purposely ignored by others!
The only way to remove this pain is to remove the cause, all the other suggestions you have seen are just postponing the inevitable!
If it is the same as me or similar, the only NHS option available is called open back laminectomy. This is a highly destructive, invasive and poorly researched lumber decompression surgery, which in the long term will leave you with as much pain and possibly worse pain than you have now!
To save yourself from a protracted period of frustration, depression and deterioration I suggest the following:
1) Source and purchase a private MRI Scan & Load Bearing X-ray,
also pay for an independant Radiologist to view it!
Make sure that the clinic you choose is as far away from your
trust area as you can phyically manage, as this will remove 'as much as
possible' any possibility of professional bias in the report's results.
The written results and plates will go to your GP, but make sure the
clinic sends you a full copy to your home. (usually a disc)
2) Ask your Consultant Surgeon politely 'but very firmly' to supply
you with information regarding the Safety & Efficiness rates of any
procedures he proposes, together with the results of all related
Randomised Control Trials (RCT's) for these procedure.
If your Consultant refuses or becomes evasive, it is because like
most NHS Spinal Units, they don't record or keep this information.
3) Research the 'spirit lifting' information you will find on the
following web site links.
www.spinal-foundation.org
www.bonati.com
www.laserspineinstitute.com
www.microspine.com
NOW compare the available written evidence of the 'Minimaly
Invasive Spinal Surgery' (MISS) (ELF) (ELD) ect: against standard NHS
open back decompression surgery! There is very little NHS evidence so
it will not take long! Your Consultant will probably say their surgery is
Minimally Invase, it's not! Do your research!!
4) For pity sake! Just like I did, Book an appointment with Mr. Martin
Knight ASAP.
The NHS will brief against Mr. Knight and his treatments 'off the record'
and you may be swayed, but just ask them to repeat those concerns
in writing and see what they say!
They will probably refuse NHS funding for this 'cutting edge' treatment
Stateing a lack of clinical evidence, dont be fooled, compare the
available research. You will wonder why they all don't do ELF &ELD!
With regards to to your sagging bottom, its probably just muscle wastage, this is caused because your other leg is carrying most of your total body weight as it trys to protect the leg with the transfered pains in it. This is normal for this illness and can be put right with excercise after surgery.
Do you research!! Its the best way!! No one will care for you like you!!
PS: Use a good Osteopath to check you all over, even if they can't locate the pain source, they should be able to rule out other possible causes and thereby eliminate red herrings and save time!
Best of luck!!