What Causes Uncomfortable Feeling In Stomach With Fluctuating Blood Sugar?

Hi, I am experiencing queasiness in my stomach, not quite nausea, which then makes me dizzy. I am pre-diabetic (A1C @6.1) and I've noticed this queasiness is related to what and how much I eat - but not always. When the queasiness happens I have taken my glucose level to find a correlation, but can't find a pattern. It happens when my blood glucose is low (near 100), normal for me 120-135 or high 189-221 (very rare). This has been going on for over 6 months and has become more frequent. Very infrequently, my head will suddenly spin making me dizzy and nauseau. Again, no pattern on this. My body is colder than usual.