Thanks, everyone.
Yeah, I talked to my vet yesterday about the special food, but he didn't want to try them yet because he's not sure if it's crystal formation that's causing it or a bacterial or stress thing. I guess that if it's not a ph problem that's causing them, it can actually make things worse. Although we didn't switch brands of food when he moved, the formulation is probably different, so it could very well be that.
We're switching to clay litter because he used that without issue in the States, although they don't sell his brand here (Hartz PH 5, cheap but the best stuff for his particular chemistry). It may be the wood litter we've been using. My cat has Pica, and he's taken to eating the wood pellets if we're not careful, so this might help. His non-food of choice is paper, though.
He's on an antibiotic, Cystease, and Metacam. After he gets better, we need to have him lose more weight, but he's not eating much right now. The vet is covering all bases in terms of cause because he couldn't get a urine sample due to my cat's bladder being empty.
Regarding me, I know a new environment is probably the reason, but I was hoping to escape it because I do have a great constitution. I've moved around a lot, including other parts of Europe with no problem whatsoever after minor adjustments to water changes (a huge sensitivity of mine). It's probably age because I started getting ill more often a year or two before the move. However, this family is ill all the time, so I am begining to think there's something in the environment (their pets maybe).