My vet called me at work and sounded quite concerned about Storm. He said that if he really does have calium oxalates in his urine that he'll need to be a special diet for the rest of his life and possibly take some kind of capsules too. Now I'm worried and hopefully he won't become sick again before he has his next urinalysis.
The vet this morning acted like there was no clear answer as to why Storm became ill. There was another vet on call too and I liked her much better because she was quite informative about the crystal situation and she didn't like to rush things as much as the other vet. Unfortunately most of Storm's care was given by the vet that wasn't as good.

Thanks again everyone. Storm's doing great and loves his new food. Before I could open the door tonight, he was meowing very loudly. He's so glad to be home.