update:
took Mowana to the vet today. His bladder was completely empty so they are keeping him until it's full (but they said it sometimes takes 36 hours to catch them with a full bladder) then they will put a needle in his lower belly to get a sterile specimin of urine and test that for a UTI and for crystals. if there are crystals, they'll do an x-ray to look for a stone. if he won't keep urine in his bladder (he won't have a litter box, but if he pees anyway) they give him Lasix and then hold him until he has a full bladder!
just waiting on word from the vet. poor little thing. as annoying as he can be sometimes, i miss him already.