I had a crazy thought, I've been bitten by a black widow before and some of the symptoms, elevated heart rate and pain, rigid guarded stomach, were similar to this. Not sure if that could be it, but awful as that is, I'd prefer it to some serious problem.
So far I have no better guess, he had no gastronomic symptoms. Still trying to figure it out, but very glad he is feeling better, and thanks so much for the good wishes. I'll post if I find anything out.
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