Welcome at HCM.
I have read the complete details given by you.
It looks from your details that most probably you are having spinal canal
stenosis.In this diseases there is narrowing of hole from where nerve
exits from spine.This can be there due to prolapse disc or extra bone(osteophyte
).You should have MRI
SCAN of back for this.Depending on reports your doctor may be able to give you treatment by medicines or by surgery.
Hope this all will help you.
With best wishes.