Step 388: Those awful shoes will never change their ways
If they are a size too small, but you bought them anyway because they are vintage, they will never fit your feet. If they cause sharp, stabbing pains whenever you wear them too long, it is not your foot that is the problem (and also you might be doing long-term damage).
If they are too narrow, too blister-y, too anything other than relatively comfortable items that protect your feet from the dangers of the ground, then give that shit to Goodwill.
One important caveat: If the shoes are made of leather, they can be stretched slightly for size and width by a trusty shoe guy. I’ve done this with a few pairs of too-narrow cowboy boots. So that’s worth a shot. But if that doesn’t work, SEND THEM AWAY FOREVER.