Chronic pain and depression. Any advice?

Hi everyone. My dad (74), a diabetic, has a chronic anal fissure that won't heal for over a year despite all the treatments. He's become utterly depressed and anxious. He stopped doing sports, sits at home all day, often naps, and consequently can't sleep at night, tormented by dark thoughts and pain. He doesn't want to see a shrink or a priest. This living nightmare has begun to affect my mom. I don't know how to help except with their chores, looking for specialists, etc... any advice?