You don’t need to worry about refeeding syndrome with a fast that short. If you’re lightheaded, you need salt - not sugar. Please do some research and read up about electrolytes before attempting to fast >24 hours.
It’s always a terrible idea to drink Gatorade unless you are 3 hours out on a marathon or similar…
I wouldn’t worry too much about any shifts in your electrolyte balance; 63/72 hours fasting can easily be managed on just water, although it’s the much better idea to take supplements. Nor will the Gatorade be more harmful than they normally are, it will cause a spike in insulin and cause you to feel much more hungry and craving, but that’s about that.
Take it as a great learning experience on the fasting path..
Egg, avocado, canned tuna are my preferred start up foods, a Japanese miso soup is great as well, add some extra soy sauce to get a good sodium boost ;)
Well done with the 63 hours btw!