For 2years I Have Been Experiencing Sharp, Burning And Debilitating

For 2years I have been experiencing sharp, burning and debilitating nerve pain in my left thigh. It started while I was climbing 95 steps in Italy 3-4 times a day for 11 days to reach my B and B. The Dr said it defied anything they knew. Physio was recommended and I have seen an osteopath, masseuse and physiotherapist for the last 2years. The physio suggested sciatica. I am doing the recommended stretches but am still in so much pain. What is wrong? What. May be the problem? What should I do?