Cider vinegar is one of those old-timey right-there-on-the-pantry-shelf fixes-everything substances that our grandparents (literally) couldn't have lived without.

Yes, it's acidic.

It's used (still) by the sort of people who raise prize winning rabbits for State Fairs to keep the little critters healthy and shiny. (Yes, I've done it, too.)

A lot of old fashioned potions have cider vinegar as one of the major ingredients. Don't laugh - those old wives generally knew what they were talking about.

So I'm not surprised that honey & vinegar is used in a stomach settling potion. Honey is another of those Very Useful Things, BTW. I'd use honey and vinegar for a sore throat, and drink peppermint and chamomile tea for an icky tummy. But if it works for you...

And yes, I've also made a vinegar pie when there was no lemon juice around.