What Causes Twitching All Over The Body?

hi i have sciatica,twitching all over my body,like a vibration from my feet up to my thighs, my doc says i have muscle wating in my right arm,had a blood test was fine,had an electromy into my muscles that showed i didnt have m.s,i can hardly walk and had to give up the gym,get 2 hours sleep a night if that, im in so much pain,put on 1 half stone in 12 months as food is my only comfort now,i dont have a life and have to get taxis every where now.