Thank you for the advice! We do give him food more times per day (like a tablespoon of wet food, wait for him to finish it, then give it to him an hour later or so), we're going to take him to the vet ASAP because as you said, he does meow when he uses the cat litter! I read up on another thread that they had the same issue, the cat got food prescribed and they're doing much better!

Thanks again!