Yikes! I have never heard of this but I am a big fan of raw milk when it comes to anything having to do with teeth, especially. I just posted about it under crumbling teeth before I read yours. It has been a real toothe saver for my 8yo. Check out Sally Fallon's book Nourishing Traditions, and the book by weston price called Nutrition and Physical Degeneration. A real testimony to what a good diet can do--and what constitutes a good diet-- lots of cool pictures of people untouched by sugar and white flour, (or toothbrushes) with perfect teeth and jaw structure. Also few fertility, weight, illness problems. The diet was the difference.
Hope this helps, and I hope you will let us know what the spots are if you find out! Puzzling. Best wishes, Kathy