is the pee stain normal color and size? how about the litter box, is the amount you are scooping normal? if it is smaller than normal, that can indicate bladder/urinary tract infection like the others said. if nothing in your life has changed and he's been a normal kitty for 7 months, it is vet time. cats are pretty intelligent and although they can't talk, they can definitely let you know that something isn't right. best of luck to you and the fur baby!