Supplement enough electrolytes is what could take the edge off. Legitimately keeping track of quantities.
Also “Only made it to day 4”. I’ve seen this somewhat dubious and scary trend develop that everyone is seemingly trying to one-up some invisible opponent or others by going for longer and longer fasts. A 96 hour fast is already quite adept and anything longer than that on a regular basis can be quite draining on your body and mineral reserves. Take care of yourself and don’t overdo it please. Fasting is about the journey, not achieving the highest number of days fasted.
Edit; you might also want to look into ketosis for managing migraine headaches. When the brain runs on ketone bodies there seems to be a benefit for this condition. Incidentally, this is also what happens when you are fasting long enough.