But Dr Jan van der Merwe, head of the Input Pain Management unit at St Thomas's Hospital, London, told BBC News Online it was difficult to take conclusive findings from looking at brain activity because so many things were happening at the same time.

BBC: Brain to blame for mystery back pain

For instance, at times the pain was so bad that all I wanted to do was lay in bed, but Dr Thomas has encouraged me to go out for a walk, or to sit in the garden.

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