Shortage of water? How long are your rides? 2 bottles is usually enough for a 3 hour ride if I stretch it. A big mistake many riders make is trying to hdrate on the bike. I don't wate to hydrate on the bike, I start the night before. Especially while prepping for a ride with 10,000 ft of climbing. Prep the body ahead. Make sure your organs have plenty of fluid before you hit the road.
ON another note, I do migraine headeaches now and then. Had them since I was about 12 yo The doc calls it an aura. I see bright lights, lose half my vision and can't see for 30 minutes or so. But my aura is usually followed by a BIG headache and some serious puking! Always fun!
I do have the latest meds. Maxalt, really helps!