Do you wear insoles in both shoes or just on the affected side? They're called Walkfit Platinum (from Boots), made of something firm and plasticky, not utterly rigid but firmer than, say, silicone or foam insoles. I only have pain in one foot, but I don't want to make myself lopsided more than I already am 
Getting some relief wearing insoles, applying ice and taking naproxen throughout the day, but the foot that's okay doesn't really love the insoles, which kind of rub on the instep.