My husband gets this sometimes for weeks, a really bad case of it. It can wake him in the middle of the night at times, and then it goes away for weeks, months, or years. Each time we try to narrow down the cause and never really figure it out. For me, once in a while I have upper GI pain, heartburn symptoms, and almost always I can blame being constipated. Rarely, I have other random upper GI pains, and again almost always from being constipated. Sometimes it’s like pressure in my chest, that you might fear it’s a heart attack. Sometimes I get pain in what I perceive to be my stomach when I eat sugary items, but this is not reflux, it is towards my left side where the stomach organ is. It can happen days in a row and then disappear for a very long time like my husband’s thing.