Thank you, everyone! Your prayers and support help so much! Barbara, thanks for the idea of calling the hospital directly. They were so nice and helpful! When I called, they were drawing blood and said they'd have DH call me back (I took that as a good sign). He said they're running all sorts of tests to see if it's cardio or GI or what, but that the pain's diminished and he's feeling a bit better. He said for us to stay put and that he'll let me know as soon as he knows anything.
So of course I'll still worry
but it sounds like he's getting good care.