Welcome to the board!
If there are sores that won't heal or are getting worse, he does need to see a vet, petpapa. It doesn't sound so much like self-inflicted wounds so much as lesions. You'll need to find out exactly what you're dealing with before you can start to fix the problem.
So I think a vet visit is your best bet.
"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."