The symptons you describe can be attributed to Carbohydrate withdrawal (If you haven't cut down on carbs before you started)
The body gets fuel from food you eat i.e. carbs (Normally)
Without the carbohydrates, the body starts to deplete its glycogen stores and eventually enters ketosis to use stored body fat as fuel instead (Due to lack of a sufficient amount of carbs)
The changeover from Carbohydrate fuel to Ketone fuel is what can cause people to shake and generally feel sluggish and/or tired as the body needs time to recompose itself and adjust.
I wouldn't worry about it, it doesn't happen to everybody, the feeling should pass within a day or two (When fully into ketosis) as your body will have adjusted to the changeover.
Hope that helps (I feel like a doctor!! lol)
*NOTE* I am not medically trained in any way, I read an ebook a while ago called 'The Ketogenic Diet' by Lyle McDonald, interesting read and is where I get most of my information regarding Ketosis from
p.s. If you're in Ketosis already, the dizziness could well be low blood sugar as has already been mentioned, I get it when I stand up too fast or make sudden movements, It passes after a couple of seconds but it can make you feel uneasy!