Not even water quenches my thirst?!?

okay, so for some strange reason i'm always really thirsty, but never feel satisfied. I drink water a lot every day but no matter how much i have it's not helping! It's riving me nuts and i feel horrible and i need to quench my thirst but nothing works! for some reason i'm also craving juicey fruits like melon, watermelon, and pinapple, which i dont have. So why doesnt water quench my thirst?