Worms would make him eat more, as the worms would be taking the goodness out of his food. They would not make him drink more either, but drinking a lot could be a sign of kidney problems. Get him checked now before whatever is it gets worse.
Sorry, I should have pointed out it's only the wet food he seems to have gone off. He still munches away on the dry food but will get him to the vets anyhow.
If he`s not eating the wet food, he`s drinking more to compensate for the lack of moisture in the dry food. It doesn`t sound like anything to worry about to me. Try him on another type of wet food. Maybe his preferences have changed. If he wasn`t eating at all would be when I would worry.