Hi and thanks for the details.
The doctors are labeling this as degenerative disc disease which dissolves the disc between the vertebra and causes them to compress the nerves exiting in between them. An MRI of the lower back will clearly define this condition and can confirm the diagnosis, so please do discuss the MRI findings with your doctor or at least get the report and we can discuss it here.
One thing that comes to my mind is arterial insufficiency. This happens when the arteries supplying the lower limbs get narrowed due to atherosclerosis (plaque deposition). This causes claudication pain, a pain that occurs after a time while walking or doing any activity involving the muscles of the leg. The distance which one can walk without pain is called the claudication distance, and this distance slowly decreases over time, till a time that the arterial insufficiency is so much that it causes rest pain, that is pain even at rest.
This can be confirmed on a CT Angiography. And the treatment depends on the percentage of the lumen blocked.
So, if this is degenerative disc disease, you should ask your PCP for a referral to the Neurosurgeon, in case this is arterial insufficiency, you should ask to see a Vascular Surgeon.
Let me know if you have any other queries about this.