What Causes Temporary Tremors. I Do Have Degenerative Spine With

what causes temporary tremors. I do have degenerative spine with many surgerys since 1980. The most recent in 2011 = two six inch rods were put with complication. A blood clot went to my heart and stopped it. I spent 6 wks in Mayo to remove spinal cord pressure and learn to walk. I have had hand shacking for about 40 yrs and recently the head and voice shacking I am 71 now