I wonder if you started experiencing the brain fog, being dizzy and lightheadedness after you started on the magnesium droplets? I think diarrhea is also a symptom of taking too much magnesium. If so, you might consider not taking it for a few days to see if the problem goes away. I believe if you have a healthy level of sodium that it will naturally help regulate healthy levels of magnesium and potassium without having to take supplements.
Taking 2 spoonfuls of PHS at once is probably not a good idea and can be damaging. Yes, we need more salt that usual because cutting out carbs (which used to help us retain salt) means we are expelling salt faster than we used to. 2+ teaspoons per day, spread out over the entire day, is the way to go. I salt my food to taste and try to get a dash under my tongue a few times a day to get my daily reqs. I also like an occasional warm mug of bone broth with added salt and will also put a few dashes in my coffee. But if I am taking so much salt at once that it makes me grimace, I know I am overdoing it.
Hope this helps.