We've run into that problem with dogs on a bland diet for tummy upset. They get quickly bored with the rice and eat around it. We finally switched to elbow macaroni with the boiled beef or chicken. So it might not be that he's worse or feeling poorly--he may just be bored with the rice.
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."