When I read your post, I was looking for answers, but now I feel that I may have some answers for you. I too have been walking with a limp over the past few years. At first, it caused no pain, but after a while, I began to feel pain in my back, especially after walking long distances.
I think the problem is related to the spinal column, especially the lower back. I think my lower back problem has been caused by walking significant distances while carrying heavy bags. You might want to read up on the spinal column, herniated disks, and spinal decompression.
A few years ago, I tried using an inversion table and after three days, I found that my limp was gone. Believing that I found a solution to my problem, I continued to walk while carrying heavy boxes. This only aggravated my problem. I only recently acquired an inversion table and started using it regularly a couple weeks ago. The results are not as quick as they were two years ago because I allowed the problem to persist too long.
If you don't know what inversion therapy is, look it up on the web, you will find many articles. You will also find demonstrations for inversion tables on the YouTube.
It is starting to work for me now, but it will take some time. The sooner you start, the easier it will be for you to resolve your problem.
I hope this helps.