I really don't think we made the wrong decision to go to the ER. The doctor didn't think we'd overreacted.

Definitely not. And I've been in the position of realising after the fact I once got that call wrong - a few years before the attack of acute pancreatitis that hospitalised me, I had one almost as bad, but just put it down as really, really bad backache and tried to outlast it, and fortunately it burnt itself out. The second one didn't, I still felt like an idiot for ringing for an ambulance, but the A&E consultant took one look at me and shot me full of morphine, then pushed my trolley through the diagnosis process himself. Better to err on the side of caution and let the experts judge.