I aint no medico, but I did have this problem last year. unlike normal heartburn, it didn't go away. Apprently, the most common cause is Acid Reflux, where the valve at he top of the stomach weakens, allowing acids to enter the gullet. In this case symptoms can be worse when in bed or lying down, as gravity does its work. I was told other causes could be a hiatus hernia, as you suggest, or an ulcer. In my case, non of the over-tyhe-counter remedies worked, and the doctor put me on "Volteron" (I think), which is used to treat ulcers. this was bleedin' usless as well. After 3 or 4 months of feeling like I'd a boiled sweet stuck in my gullet, I eventually had an endoscopy, a camera being sent down the throat to see what's going on. Everything was clear in that. The symptoms disappeared of their own accord about another 3 or 4 weeks later, which kind of suggests it may also be linked to anxiety. Anecdotal evidence seems to suggest that this is pretty common amongst men and women of my age, (just turned 40), and does often go away by itself. Worth a visit to the doctor, though, especially if it's still there after a couple of weeks.