I drink 2 gallons of plain seltzer water a day, have migraines, tired, and eat healthy....I know I need salt and potassium because of the amount of water so I eat accordingly. I m also amneic, but try to take iron supplements every other day,but still constipated....what s going on?? I m not diabetic, and in fairly good shape 5 7, 145lbs. I never eat fast foods and try to eat organically when possible. I m also on imitrax and effexor. Thoughts??