Hi Penny, if your levels of vit D are good, then theres really no need to take it, so I wouldnt worry about it, but my advice would be the same for you as for Ocean, make sure your doctor knows about the reaction, and investigates other possible causes for it, just in case there is something else going on.
Also it can sometimes take a long time (months) for magnesium levels to go up to correct levels, it can be difficult for the body to absorb in supplement form, so its a possibility that it was the vitamin D causing the magnesium deficiency symptoms to occur. In my case I was taking 50,000 iu of vitamin D a week and large amounts of magnesium, and it took about eight weeks of taking the magnesium before I stopped getting a reaction for a few days every time I took vit D, (muscle cramps, pain and twitching, heart pain and palpitations, fatigue etc) but it all came right in the end, and I feel a lot better. So maybe your magnesium levels were still a bit low?? But tell a doctor about the reaction, just in case.
All the best