Dizziness is not a detox symptom. It is due low blood pressure. One needs to take a deep breath and stand up slowly when this occurs. After a few days this will pass when your body adjusts to no food coming in.
So do not worry about dizziness, just breath deep and stand up slowly.
I agree doctors do not know and like fasting. If everybody was fasting and feeling good, they will lose business.
Yes, find another good doctor or better yet, a naturopath.
I am glad to hear that you have a better control on your food consumption habits.