What I was thinking was that Iodine somehow triggered a calcium issue. Kidney pain / high back, I would think more bromide related. Low back pain / muscles; like I suggested above.

The reason why is the interesting (at least for a nerd like me:); lets say 4-5 persons in a family take Iodine in pancakes or whatever.
One get low back pain, why dont the others? Iodine in my experience seemed to "highlight" whatever problem I had, while my sons and other cases got very different effect of it. Yes I quit a few times in the beginning, until I realized it was me/my health issues.. not the iodine:)

Could also be a boron deficiency, as it is a key in calcium, magnesium, vit D utilization. Kind of bring these three together. Also it is the main mineral for the parathyroid (according some knowhows) that again has a big say in calcium issues, calcitonin etc. Same as iodine is the main mineral for the thyroid.
http://drsircus.com/medicine/magnesium/magnesium-deficiency-symptoms-diagnosis

what do you think is causing this? low hcl?
i used to feel terrible after eating fried foods.