Your description sounds exactly, to the letter, like what I am experiencing.
I had a stomach virus
in June, followed by a week
or so of discomfort and nausea, and one bout of severe nausea following a high fat meal.
I had a sonogram and a gallstone was found. The gallbladder came out, but the same feelings I had before the surgery persisted: intermittent, random bouts of nausea and dizziness, centered around BMs.