I just bought a new litter box for my cat last month and ever since I got it, my cat barely uses it. He's using it on the floor. He had his old litter box for 10 years. I don't know if it's because he misses that one or what it is. His stool is also runny all the time...and sometimes a little bloody. He sleeps a lot at times, too. Any idea of what it could be? We can't afford a vet.