Distilled doesn't taste good but there is nothing bad about it. There is no need to go to the hospital. Call the doctor and update them if you have a seizure. The hospital can't help us anyway why pay the money to be told that?

Distilled water the clearest sterile water on the market as it has no minerals unlike bottled water made for drinking as it has minerals good for the body. That would be why your stomach is feeling a bit upset. You could ask your doctor next time visiting what is the best type water to drink if you have stomach issues as there are different alkaline levels of water on the market. That is my best suggestion.