The magnesium; oxide is not the best, quite insoluble and hard to utilize. Citrate, malate, glycinate are good ones. Try to get one without to much fillers / coatings.
You can get them as powders as well. Magnesium chloride is an option, aka magnesium "oil", can be taken internally as well as externally.
Same goes for all supplements; I now have them all without this, except for a little magnesium stearate in my C capsules. The difference is that you can take these without food, while the other ones I highly recommend to take right before food.
The heart racing can be magnesium deficiency. Also invest in a good salt; taken daily this helped me more than anything, before iodine. I had palpatations and heart racing / pounding en masse.
"Thanks so,much for your advice? I was literally crying the other night from being stressed out not understanding how to do the Iodine Protocol and the fear off the rest of my hair falling out...or having the Acne all over my face....."
-haha, relax. If this was the case this forum would be dead, long time ago !!!
A little bromide Acne can be expected, but this is trancient, and only when you proceed a certain amount of iodine, like 100 mg. The hairloss; take the selenium methionine in a good ratio to iodine, like 100 mcg of selenium to 50 mg of iodine. More if you live in a low selenium area like parts of Europe. Also consider zinc, vit E.
12 mg of Iodine is too little, but start somewere; titrate up. The good things happens at 100 mg IMO.