Dizziness on Pre-Op?

I'm on day 8 of my pre-op diet - two protein shakes a day and a salad w/protein for dinner.  I'm doing ok, but then suddenly last night I started getting really super dizzy.  I've been drinking a lot, so I don't think that's it.  Did anyone else experience the dizziness?  Did anything help alleviate it?

I have not begun my pre-op diet. I was wondering how many carbs are in your protein shake? You may notice that you are urinating more often. Your body is getting rid of your glycogen stores in your muscles and liver. The break down of glycogen releases a ton of water. So you need to make sure that you are replacing sodium, magnesium, and potassium. Try drinking propel or G2 Gatorade as they have electrolytes in them.

I am not a doctor. This is just my opinion.