magnesium

All my research shows that people with Lymes are deficient in magnesium. I have read 2 posts by Newport saying "if you're going to supplement with magnesium, be prepared to do battle". Can anyone tell me why? I searched for more info, but couldn't find. I realized that my poor body has indeed become even worse since being on magnesium for about the last 7 months. It does help me to sleep a bit. I take magnesium oil orally in water daily. Am confused, and grateful for any input.

Thanks so much!