Soy can be very allergenic in dogs, so I'd cut out the black soy beans. How big are the brown spots? Are you sure they aren't just changing pigmentation? I know our dogs get dark spots on their bellies as a normal age-related change...
"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."