What Can Cause A Bump On Back With Smelly Pus ?

I have one recurring/constant bump on my upper back and it continuously is full of white puss. The white never shows like a "white head" just an underskin bump but when you press on it a huge amount of white "pimple" like puss comes out....daily. And it has a bad 'cheesy-feet' odor to it...why is that? Could it possibly be something other than a pimple?