Suggest Treatment For Pain And Tingling Sensation In The Back

Hello I am a 38 year old male with neurofibramatosis involving the entire spine. Yesterday while walking I took a slight large step and my left leg, the one taking the step lost all feeling upon reaching the ground causing me to fall. (No injury). This happens from time to time but usually I get kind of a warning sometimes I get a tingling sensation in my back and I know to be careful or I will have a sharp pain in my knee and I know not to put weight on that leg. Should I be concerned with this somewhat new symptom.