Heartburn during IF

I’ve been having heartburn during intermittent fasting. I’ve been intermittent fasting for about 4 months. Intense long heartburn started happening about 3 weeks ago. I was doing 20:4 or 18:6 depending on the day. Not stuffing myself. Not lying down after drinking liquids. I’m not getting this heartburn after eating. I’m getting it 14-20 hours into my fast. YouTube health critic suggested apple cider vinegar to help the esophageal sphincter close, tried that for 2 weeks, nothing. Tried cabbage everyday for two weeks. No. Went off IF for 2-3 days, gone. Fasting, back. Anyone else? Anyone find a fix? via /r/intermittentfasting https://ift.tt/7QWFCXt https://ift.tt/h4O0Zk3