My wild guess "diagnosis" would be some sort of gastrointestinal bug rather than just dehydration. Your symptoms seem to match that and you indicated your cramps were mainly in your gut, not your large muscles. The cold sweats suggest a fever, which also fit a GI bug. Dehydration could could be a contributing factor, if not the primary cause. Excessive water intake, alone, can cause vomiting, but usually not diarrhea. It would be a good idea to see your doctor for a real opinion.