What Causes Buzzing Feeling In Body With Body Shaking?

I will start off having a buzzing feeling in my body, then either my head will jerk to one side or my body will start shaking. At times I will lose the ability to talk and during these episodes I see people and know they are there, but I feel like I'm not there. More recently I felt some pressure on the top of my head, then my eyes started to roll back and then I preceded to start shaking.. I had a MRI and eeg done, and they both came back clear.. so what is going on?