Thanks, everyone! I'm feeling much better. I've been making a huge effort since it happened to get enough fluids; I struggle with that when the weather isn't warm. Not being adequately hydrated could definitely have been a contributing factor.
And I can't say enough about how warm and comforting my poncho was for the occasion! Of course when I decided to wear it as my outer layer to go to work, I had no idea I'd be in the ER later. But if I ever have planned time in the hospital, it will be the first thing I pack.