Spinal stenosis

Hi all Specialist Surgeons !
                                    I have been having this pain for over 3 years now , it runs down the front of both my legs below the knees and it feels as though someone has kicked me as hard as they possibly could , at the same time I get chronic pain in the mid to lower part of my spine in my back and it nearly makes me blackout and sweat profusely , this has only occurred since a car crash just over 3 years ago and it is getting progressively worse, I cannot stand for very long unless holding onto something and I can only walk about 15 to 25 yards maximum without excruciating pain ? and having to sit down !

I have just been told by the last specialist that I saw that he thinks that I have spinal stenos-is in my lumbosacral spine region that has just manifested after this car accident and has persisted since, any suggestions from anyone please

Can anyone please say what is causing this problem ,  and what is the cure if anything , would an MRI scan help with this , or what is the answer please.

Regards
             Steve