A hot stone embedded in the middle of my belly. That’s what the nagging ache felt like when it asserted itself abruptly one evening—a distinctive new addition to the repertoire of usual gastric phenomena I’d experienced over decades of stomach ownership. Like anyone else’s, at one time or another the old tummy has felt queasy, nauseated, acidic, cramped, gassy, growlingly empty, pleasantly full, and Thanksgivingly overstuffed.