Thank you for your advice. I went and got my hands on some distilled water and did research and it's true that the spring water I was drinking is definitely not as "pure" as distilled or even purified water.
I drank some and it seemingly gave me temporary relief, so you were right in that the water brand I was drinking was part of my problem.
However, I still feel the acidic pains in my stomach returning, so I hope as the fasting goes further, it will stop or maybe I can find another alternative as well.
But I'm glad I took your advice as even though it was only temporary, it was a relief to get away from the pain. Thanks again.