He definitely has crystals in his urine, there is no question, and you need to take him to the vet. He may need an acidifier, I use carpon by doctor belfield and we have no more crystals. My guy was nice enough to pee on a piece of plastic for me, so I know what they
look like and feel like (sand). That sand is scratching the inside of his uretha, and could become a plug and block him, which could result in death. Don't mean to alarm you, but be alarmed very alarmed :-) this is serious stuff. go to the vet asap and before you go leave out an empty litter box , so you can take a urine sample with you. If you get it a day before, keep it in the fridge overnight, it will still be good. good luck.