...is the nexium helping at all, or what?
If so, the doc's likely on the right path - could be an ulcer (or maybe even just some kind of "stress induced" acid reflux kind of thing maybe).
If not, I'd be calling that doc
before lunch and getting some answers and other options. (Says the guy who only goes to the doctor when he's forced to do so...
)
Whatever it is, I hope they get it figured out and get you back towards normal before long. Love and best wishes to you, Mira-dear.