Suggest Treatment For Leg Pain Caused After A Damage To The Ulnar Nerve

I had nerve damage to my ulnar nerve in my left arm about 4 years ago and since then i have had leg pain in my left calf and behind my knee. The only thing that seems to relieve the pain is walking. The doctors have no clue what is going on. I cant sleep because lying down hurts my leg. What do i do? I am 5' 8" and i weigh 155 lbs and i am a marathon runner. I rarely get sick>