I have had the exact same symptoms, about a week or so after going gluten-free, I had terrible dizzy spells, low blood sugar, etc. Eating every couple of hours seemed to help. The dizzy spells only lasted three days. I went to the walk in clinic and I think the Dr. thought I was crazy (my blood sugar was really low). Now it is 2.5 weeks later (a month now gluten-free) and the dizzy spells, brain fog, etc. have come back, almost worse than before. I feel like my head is floating in a fog, I also feel nauseated after eating. I feel better knowing I am not the only one, I thought I was over it and I'm scared these symptoms have come back. I have not felt any better since going gluten-free (I only have hypothyroid symptoms, no GI symptoms) and I hope this changes soon!