I am sorry that you are not feeling well. Those episodes must be terrifying.
I had problems with dizziness when I had my IUD and it too seemed to get worse after I ate. Shakiness also accompanied many of these episodes. I went off Mono-Sodium-Glutamat (Natrium Glutamat) and artificial sweeteners until I realized it didn't seem to be helping. In response to my post, I was told that the hormone in Mirena (levonorgestrol sp?) can cause insulin resistance. I also received some other helpful information in response to my posts so you might want to read them. I would also try doing research on reactive hypoglycemia. My knowledge of medicine is pretty poor, but this is one of the conditions I thought I might have when I was experiencing side effects similar to yours.
As for the pill, I too was on it for awhile, albeit when I was much younger, and didn't have severe side effects. I had the MIrena removed almost 3 weeks ago and within a week the dizziness that had become more and more persistent disappeared. I wish you the best and hope you feel better soon.