Completely agree with April2 ... but would like to add that a small can of tuna and water is probably not enough of a meal either. You could, at that point, actually be hypoglycemic (too little sugar). You may want to try eating small regular meals (6 per day - 3 meals, 3 snacks) as a way to better way to regulate your food intake. Would certainly get a fasting blood sugar done to see where you are medically ... could be a one-time occurrence, but could be a precursor to diabetes.
Hope you are feeling better ... take care of you!
I've had this happen to me. Your blood sugar probably got out of wack a little bit by going very high with all the sugar and then crashing very low. That would explain the dizziness, feeling lightheaded, nauseas and even shaky. Your body will adjust back again in a day or so. Just drink plenty of water, get rest and try to eat healthy with a little protein in each meal. Protein helps stabilize your blood sugar.
You may want to get your blood sugar tested periodically for possible diabetes too. Just be careful now that you know how you react to sugar.
I hope you feel better today!