You can try ultra-pure Ancient Minerals magnesium oil sourced from an ancient seabed a mile deep underground. This magnesium lay untouched for millions of years. BTW, usng nigari as a source of transdermal magnesium chloride is probably less than ideal, especially if it comes from the Sea of Japan, which is a known source of industrial contaminants and toxins (although I don't know if or how this product is filtered).
Ancient Minerals magnesium oil can help with heart palpitations, but also with other heart problems. It also relaxes tight muscles all over the body, partly by counteracting the effects of calcium at the cellular level. Calcium rigidifies tissues. Magnesium relaxes tissues. Magnesium Oil (magnesium chloride) can relax muscles rapidly, and can raise magnesium levels in cells much more quickly than oral forms of magnesium. That's the beauty of Transdermal Magnesium Therapy (TMT). It's fast.
You might also try Nascent Iodine (also available from Integrated Health), which is an atomic form of Iodine that the body immediately recognizes and uses. Do not confuse Nascent Iodine with radioactive iodine (which kills your thyroid). Instead, Nascent Iodine is a non-toxic form of iodine that remains energetically activated after you take it for several hours, and can powerfully energize you, including your thyroid. This form of iodine is suitable to take multiple times per day.
Nascent Iodine promotes detoxification, especially of toxic halides like chlorine, fluoride, bromide/bromine. In fact, iodine is probably one of the only non-toxic halide (except for certain types of natural salts). We are so poisoned by chlorine in the water, fluoride in the toothpaste, bromine in breads and fire retardants, etc. All these chemicals were supposed to help us, but actually are killing us!
Toxic halides like chlorine and bromine block iodine receptors and prevent iodine assimilation. This assumes you get enough iodine in the first place (96% of Americans are iodine deficient as determined by a standard loading test). Try Nascent Iodine. After you replenish your iodine levels, then you produce more energy (ATP) in your body and dramatically can improve thyroid function. It also is known to support (and/or eliminate) thyroid conditions, including Graves disease and Hashimoto's disease, as well as defects in iodine assimilation (e.g., damaged sodium/iodide symporter) in the human body.
Nascent Iodine stimulates the release of the toxic halides. According to Dr. David Brownstein in Iodine: Why You Need It, Why You Can't Live Without It (3rd ed. 2008), it is critically important we detoxify these chemicals because an excess of these poisons (combined with an iodine deficiency) is associated with a higher incidence of cancer.
Dr. Brownstein asserts that cancer is multi-factorial, but finds overwhelming evidence for the the role played by iodine deficiency. Equally overwhelming for him is the evidence for the toxicity of bromine, for example, being found in higher levels (relative to iodine) in cancer patients. For more info, read Dr. Brownstein's book (which you can find used on the web for less than $10).
Dr. Brownstein also notes that iodine works better when it is taken in conjunction with vitamins (e.g., B-vitamins) and minerals (like magnesium and selenium). He advises patients taking iodine also to engage in holistic nutrition program that includes a high-quality multivitamin and mineral formula. (In this program, you avoid brominated bakery products and sodas containing brominated vegetable oils, like Mountain Dew. In fact, you should avoid all refined grains and sodas!)
One of the main reasons Magnesium Oil complements Nascent Iodine is that magnesium helps iodine work better. And chlorides (as in magnesium chloride) also help detoxify halides like bromine. So magnesium chloride (magnesium oil) and iodine act together as a team.
In terms of energy production, the combination of Magnesium Oil (magnesium chloride solution) and Nascent Iodine is ideal for supercharging energy levels. That's why magnesium expert Dr. Mark Sircus uses Magnesium Oil in combination with Nascent Iodine, and gets excellent results.
The point is that once you start creating more energy and detoxifying the body, then all organ systems will benefit, and you start building true health. It's difficult to completely eliminate all chlorine, fluoride, and bromine from our bodies (especially if you don't have a good water filter at home), but taking Nascent Iodine at least can replenish depleted iodine levels, block excessive uptake of toxic halides, and start the process of purging the body of such destructive chemicals. Iodine can give you the energy to live your life.
I don't know if Magnesium Oil and Nascent Iodine will completely solve your problem, but they are definitely worth trying. You have nothing to lose, and much health to gain. Here is a good source for these products: