I believe I got dehydrated a few weeks ago...but the process slowly snuck up on me...like 2 weeks in 100 plus....even tho I am in my truck with AC and the like...day after day exposure....I started to get headaches and out of sorts, always tired.....had to get a room, drank lots of water to readjust my body....
Throttle back on the coffee and cola, both contain caffeine, which is a diuretic. Increase your water intake. I've got a large canister of Gatorade powder from Costco. I fill one of those squeeze mustard bottles with the powder and use that to add the Gatorade to a bottle of water. I'm as fresh and hydrated as the day I was born.