If you are taking calcium make sure you take it with vitamin a and d as they are needed for calcium absorption. Also, you should be getting enough iron if you are eating a lot of meat. iron in meat is found within the heme complex and is more readily absorbable than anywhere else. If you are doing this as a vegetarian, then that is another story. There are a lot of compounds in veggies and legumes that bind (chelate) the iron.

It sounds more like low blood sugar levels to me. I have hypoglycemia and i get like that. If you are limiting your carbohydrates so low you might have depleted your liver glycogen. Protein can only be converted so fast to glycogen. Once you deplete your liver glycogen it takes awhile for it to be put back. You exercise too right?

If you exercise try eating a balance of protein/fat and carbs before working out and after working, a snack then low carb it the rest of the day.

Also you might up your carbs to 30 or 40 % for a couple of days to restore your liver glycogen, then your dizzy spills might go away.

but it's a good idea to talk to the doctor.
suzy