I can relate to your problem. I have had almost the same symtoms for three years. I had MRI's, saw a Neurosurgon didn't find anything wrong with my back other than a buldging disk. He didn't think it would cause my feet to hurt so bad. I also had EMG's to find nerve damage. That came back OK. The calves of my legs tingle and my legs feel like they are cold. I also can't wear any shoes other than orthopedic. I thought a few years ago I would be in a wheelchair if something wasn't done soon. No Dr. even cared (it seemed).
I am on heart meds Coreg, Enapril and Hydroclorthyside. I looked up side effects of these medications, and they list tingling legs feet, feeling of coldness. Achy joints and muscles. I am beginning to think it is the medication. I am going to get with my Dr. about this. I have to get some relief. I am 55 yrs old and very active. But I have come to the point that I just cant walk, stoop, run, do housework or anything without terrible pain in legs and feet.
Find a pain specialist in your area. They are used to dealing with conditions that cause pain like yours and might even be able to tell you what is causing it. In any case they would be able to help you manage your pain. A website that helps people find pain specialists in their area is www.raceagainstpain.com. Another thought is RSD, but that typically arises after some sort of injury and gradually gets worse and can spread throughout your body. Other than torn tendons, muscles, or bone splints I'm at a loss.