Your water intake is fine. The point is to balance salt and water. I've had brief "swimmy" spells when my electrolytes were rebalancing the water content of my cells. Then things even out when I'm steady again.
I take methyl-B12 myself, as well as methylfolate (never folic acid). They're both involved in methylation. I'm just not sure of a direct link to adrenals.
When adrenals ache I agree that is a sign they are troubled. Iodine and salt are both great for adrenals, as are pantothenic acid and Vitamin C in generous amounts. If rest and time aren't enough, you could try supporting with over-the-counter adrenal cortex. Nutri-Meds makes a reliable version. Generally the most support is needed in the morning, with a gradually descending need through the day until cortisol levels are their lowest right before bed.
Besides the detox, when Iodine is raised it encourages higher thyroid hormone production. Thyroid hormone requires adequate levels of adrenal cortisol in order to get into the cells. This function, if adrenals are weak, may be contributing to the adrenal ache.