Poisoned!
Limoncello Addendum:
Raspberries and strawberries both soften and grow obvious mold when they go bad.
Blueberries, apparently, do not.
So, if you feel like tossing a dozen blueberries into your limoncello & lime, I recommend either fresh berries (for flavor) or frozen berries (if you want it chilled).
I advise against Blueberries of Remarkable Longevity* that were fresh when you bought them, like, three weeks ago, and look and taste the same now as they did then, but harbor traitors in their midst.
Fortunately, I think I only had one bad berry. The pain in my tummy woke me up whenever I rolled over, but I could just stop moving and fall back to sleep.
* Faint Necromancy; CL 3rd; Craft Wondrous Item, Gentle Repose; Price $4.00 for a set of 50, on sale for $2.25.