Could it be that your shoes keep your feet positioned in a way that is similar to the position they take when you put weight on them? Maybe their support is degraded, or the shape isn't quite right by design, or they're laced too tightly?

Then again, I've heard people claim that mankind's feet were generally healthier before shoes..

Also if the only reason you now own curtains is because they're leopard print, I'm going to smack you with a pool noodle. A really old, crusty, sun-bleached scratchy one.