what happenned to me?

Couple weeks ago, I attempted a water fast.
Little bit about myself, some kind of muscle dystrophy, slowly regressing, losing muscle strengths and mass. Can walk only holding to a wall, can get up from a chair using a table, etc.
Decided to do a water fast, didn't put big goals, but kept in mind that I would try 21 day, if not, then 14 days, if not then 7-10 days. Didn't push myself into extreme.
First day was fine, some headache, but I expected it. Second day started fine, but closer to noon developed some burping, and closer to evening got crazy heartburn. Couldn't slee all night because of this crazy heartburn. Third day started with burping and acid going back into my throat, and closer to noon got nausea. Felt like throwing up, but kept it inside, but later thrown up, seems like only water with acid taste. Then, threw up 3 more times during a night, and decided to stop my fast. Felt burning pain in my stomach.
I tolerate things well usually, and I want to try to do another round of water fast. People in the house discourage me, but I need to make sure that it won't be like the first time. I can tolerate pain and headaches, but I need to do something with heartburn.
I only drank distilled water, I have a water distiller at home, and make fresh batch every day. On my third day, I had some mineral water mixed with distilled water, I thought it'd help with acid reflux and heartburn, it did just a bit.
So, please help me to figure out what I need to do.
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