Eight weeks ago, I picked up a fever while visiting Zimbabwe. After 2 weeks it cleared up with the help of antibiotics but almost immediately, my whole saddle area became numb and both legs had constant pins and needles, although I have no back pain. Now 6 weeks on, the saddle area is 75% OK again but the pins and needles remain and my balance is affected as my brain doesn't know accurately where my feet are although muscle exercises are helping with this. X rays showed a narrowing of the L5/S1 gap. I am 56 years old, 60 Kg, 166 cm with no history of back problems - can you advise on the likely root cause?