Not only is my boy home, but he's almost back to himself. Rumbledad just brought him home, and the verdict is that he most likely had a bout of gastro-enteritis that caused the pain and fever. It could be because he's been stressed his immune system is down - he's had this and a bad bout of feline acne - but the x-rays today showed that there is no blockage.
He's not hiding under the bed (like he was yesterday) he's out and confident again. Hammy is happy (but I think a little envious that we're fussing over Rumbles so much - we're making sure to fuss over him as well).
Once again... thank you all so, so much for your support. I know that Rumbles has felt all the love and good wishes you've all sent to him, and he's sending out a BIG RUMBLECUDDLE to you all. I hope you all know how much I've appreciated all the messages and comments and the #pawcircle. Your kindness has been amazing.