When I am dehydrated I have the same symptoms you are describing. Actually, at those times I need more than just water. So, I begin drinking Pedialyte. I'm not crazy about Gatorade. When I had an ileostomy I used to head to the ER for an IV to hydrate me. Haven't needed to do that since takedown 12 years ago. Hydration made a real difference for me! Best wishes!