I think the water your doctor was talking about is what we call tonic water - which contains quinine. In addition, there are some MG patients that are sensitive to/bothered by magnesium. Be aware of your intake of foods containing a lot of magnesium - leafy greans (spinach), nuts, some fish, soy beans, brown rice, avocados, yogurt, bananas, figs and dark chocolate. It is not that you should avoid these foods, (most of them are very good for you), you should just not eat an excessive amount of them, all of the time. (and don't take magnesium vitamins unless a doctor tells you to)