I Drink Plenty Of Fluie Night Before I Go To

I drink plenty of fluie night before I go to bed then in the a.m. I drink fluids throughout the day.I work in a tree service and it happened to me today....I was fine sweating a lot like someone had poured a bucket of water on me and about half hour later I had lost strength and everything started getting real bright. After work coming home I started to cramp.How can I solve this problem? Is there something wrong with my body?