I've never heard of Four Thieves Vinegar. It sounds like something I might want to try.
There's a lot of recipes for it. Quite simple really, just add the stuff you like to ACV and let it sit 4 days and 4 nights.
I used rosemary, basil and cloves in my last one. But the recipes call for more than that. I just roll with what's on hand. If I do it again the one thing I would change is that I'd use a tea ball or strain it out after. I take a shot glass of it every few days.
My dog when she was a puppy- I cured a urine tract infection and saved a major vet bill. Then I got one last year and cured that too. My doc wanted me to use antibiotics and I said sure if this doesn't work. Week later my culture came back as clean as a whistle. He was completely mind blown.
Oh and say goodbye to heartburn too.