Have you tried taking an Epsom Salt bath? Those really help calm me down when I reach that state.
B12 alone won't help, you need magnesium and the other b-vitamins to complete the methylation cycle.
A good amound of dark leafy green vegetables can help pull things together for you. If you can buy a head of organic kale, a salad mix of organic baby spinach, or even just plain frozen spinach/kale, and then eat a half cup or cup of it steamed and gently cooked until is is softer and easy to digest, will supply the folate and many minerals that will help satisfy and calm and complete the methylation cycle. Take care with the B-12, it is best only used sublingually (under the tongue or under the upper lip). If you use it and it makes you frown, feel bad, or sad, remove the tablet, drink a good amount of water, and use it only in small amounts. Lacking folate, phosphate-rich foods with B6 in them will often show up as b12 deficiency.
DE will certainly shred the baddies to bits, but then you need a rest-period and lots of gentle excercise and fiber and peace to flush the broken-up-bits back out. Buy some activated charcoal at the pharmacist's and take 2 capsules every few hours (skip this while sleeping ;), and get plenty of water with it. Remember not to have activated charcoal close to food, medicine or vitamins, as it will bind with them and reduce absorbtion. Get that Epsom Salt somehow, soak your feet in warm Epsom Salt water and a few teaspoons salt.
for an ES back it's 1/2 to 1 cup ES in a full bathtub of steaming water, and for a footsoak, it's 2-4 tablespoons in the footbath water. Soak in either for 15 minutes to 1 hour, depending upon how comfortable you feel.
I think you may be having a toxic overload from the DE shredding biofilm colonies in your gut- activated charcoal will really help to bind and move out the toxins, and fasting for a little while can help. Fiber from apples can doubly help, but honest, adding vitamins right at the moment is just a drop in the pool.
Epsom Salts transdermally will help dilate your blood vessels and help shunt the material out into your digestive tract. You need fiber and activated charcoal or Bentonite clay to bind and stop it from circulating.
Take deep breaths, slow, long walks, and keep warm. I find easing off food to give me some relief in those situations.. but detoxing is important now. I use kitty litter baths when I am most needing to move stuff out and my liver is overloaded - I found that one of my local grocery stores sells pure calcium Bentonite as a cat litter, so I keep it for helping out when I need it. I pour a cup of the gravelly cat litter into an old pillow case, tie off the opening of the case, and then take an extra-hot bath and knead the gravel in the case to make it release particles in the water. The Bentonite is just like actvated charcoal, and it relaxes me very quickly. The body loves calcium, and the bentonite is basically volcanic ash. It pulls toxins out through the skin pores, instead of leaving them in the lymph to circulate back into the liver and to continue the cycle.
Basically toxins, particulate, and other matter that your liver needs to detox, is mildly positive-charged, or 'oxidant'. Your body operates best at a mildly negative charge, or alkiline. too much of either charge at any one time can make you feel quite sick- so bathing in, or eating, or drinking stuff that helps to one side or the other, has effect.
Bentonite clay and activated charcoal has a powerful charge towards the negative side of the scale, and can help balance you out. magnesium is also an alkiline mineral. The heart flutters, anxiousness, and jolts can be your body telling you it needs help- and also be signs of a strong need for that mineral.
I definately do not reccommend drinking Epsom Salts (magnesium sulfate)..!!! It is a really good fertilizer, and makes me get really bad thrush until my body is able to clear the infection, and I have much, much better results after simply using it transdermally. If you want to supplement magnesium, you need to buy magnesium taurate or threonate. Douglas Labs sells the best one. Other combinations like magnesium oxide act pretty much like good inorganic fertalizers.